不同剂量重组人生长激素治疗对特发性矮小症患儿骨代谢、甲状腺功能和血清Ghrelin、IGF-1水平的影响

摘要 目的：探讨不同剂量重组人生长激素（rHGH）治疗对特发性矮小症（ISS）患儿骨代谢、甲状腺功能和血清食欲刺激素（Ghrelin）、胰岛素样生长因子-1（IGF-1）水平的影响。方法：选取2017年3月~2020年2月期间来我院接受治疗的ISS患儿60例,根据随机数字表法分为低剂量组（给予剂量0.10 U/kg?d进行治疗）和高剂量组（给予剂量0.20 U/kg?d进行治疗）,各为30例。比较两组患儿生长发育情况[身高、体重、生长速度（GV）、身高标准积分（Ht SDS）]、骨代谢[骨碱性磷酸酶（BAP）、I型前胶原氨基端前肽（PINP）、I型胶原交联羧基末端肽（β-CTX）]、甲状腺功能[促甲状腺激素（TSH）、游离三碘甲腺原氨酸（FT_{3/sub>）、游离甲状腺素（FT4/sub>）]和血清Ghrelin、IGF-1水平。观察不良反应发生情况。结果：治疗1年后,高剂量组身高、体重、GV、Ht SDS高于低剂量组（P<0.05）。高剂量组治疗1年后BAP、PINP高于低剂量组,β-CTX低于低剂量组（P<0.05）。两组患儿治疗1年后TSH、FT3/sub>、FT4/sub>组内对比无统计学差异（P>0.05）。高剂量组Ghrelin低于低剂量组,IGF-1水平高于低剂量组（P<0.05）。两组总的不良反应发生率组间对比无统计学差异（P>0.05）。结论：相对于0.10 U/kg?d剂量的rHGH,0.20 U/kg?d剂量的rHGH可更好的促进ISS患儿生长发育,调节骨代谢和血清Ghrelin、IGF-1水平,且对人体甲状腺功能无影响。}     

特发性矮小症患儿治疗前后血清IGF-1、IGFBP-3、25（OH）D、皮质醇水平变化及其与体格发育和骨龄的相关性分析

摘要 目的：探究特发性矮小症（ISS）患儿治疗前后血清胰岛素样生长因子1（IGF-1）、胰岛素样生长因子结合蛋白3（IGFBP-3）、25羟维生素D[25（OH）D]、皮质醇水平变化及其与体格发育和骨龄的相关性。方法：选取安徽省儿童医院于2017年7月～2021年3月收治的88例ISS患儿作为研究组。另选取同期体检健康儿童88例作为对照组。比较两组血清IGF-1、IGFBP-3、25（OH）D及皮质醇水平。比较ISS患儿治疗前后血清IGF-1、IGFBP-3、25（OH）D及皮质醇水平,体格指标以及骨龄指标。通过Pearson相关性分析ISS患儿血清IGF-1、IGFBP-3、25（OH）D及皮质醇水平与体格指标、骨龄指标的相关性。结果：研究组患儿血清IGF-1、IGFBP-3、25（OH）D水平均低于对照组,而皮质醇水平高于对照组（均P＜0.05）。ISS患儿治疗后血清IGF-1、IGFBP-3、25（OH）D水平均高于治疗前,而皮质醇水平低于治疗前（均P＜0.05）。ISS患儿治疗后身高、体重、骨龄年龄差（BAD）、骨龄指数（BAI）以及体质指数（BMI）均高于治疗前（均P＜0.05）。经Pearson相关性分析发现：ISS患儿血清IGF-1、IGFBP-3、25（OH）D水平与身高、体重、BAD、BAI以及BMI均呈正相关;皮质醇与身高、体重、BAD、BAI以及BMI均呈负相关（均P＜0.05）。结论：ISS患儿血清IGF-1、IGFBP-3、25（OH）D水平异常降低,皮质醇水平升高,且上述四项指标均和身高、体重、BAD以及BAI有关。     

重组人生长激素治疗儿童特发性矮小症的疗效及对血清Ghrelin和IGF-1水平的影响

目的:探讨重组人生长激素(rhGH)治疗儿童特发性矮小症(ISS)的疗效及对血清饥饿激素(Ghrelin)、胰岛素样生长因子-1(IGF-1)水平的影响。方法:选取2014年1月-2016年8月期间我院收治的ISS患儿114例为研究对象。按照随机数字表法分为实验组(n=57)与对照组(n=57)。其中对照组给予常规治疗,实验组在对照组基础上联合rhGH治疗,两组疗程均为12个月。比较两组患儿的临床疗效,同时观察并对比两组患儿治疗前后血清Ghrelin以及IGF-1水平。结果:治疗后两组患儿身高、生长速率均较治疗前升高,且实验组高于对照组,差异有统计学意义(P0.05);治疗后两组患儿体重、总甲状腺素、骨龄、空腹血糖水平较治疗前比较差异无统计学意义(P0.05)。治疗后两组患儿血清Ghrelin水平较治疗前降低,且实验组低于对照组,血清IGF-1水平较治疗前升高,且实验组高于对照组,差异均有统计学意义(P0.05)。实验组不良反应发生率为5.26%,与对照组的0.00%比较,差异无统计学意义(P0.05)。结论:ISS患儿应用rhGH治疗效果满意,可明显改善ISS患儿体内血清IGF-1、Ghrelin水平,安全无副作用,促进患儿健康成长。     

重组人生长激素治疗特发性矮小患儿的疗效及生长速率预测模型的建立

摘要 目的：探讨重组人生长激素（rhGH）对特发性矮小（ISS）患儿的治疗效果,并建立rhGH治疗后生长速率（GV）的预测模型。方法：回顾性分析确诊为 ISS并应用rhGH治疗1年的130例患儿的疗效,以治疗12个月后的GV为因变量,采用多元逐步回归方法建立ISS患儿疗效的预测模型。结果：rhGH治疗6个月、12个月的身高、身高标准差分值（HtSDS）均逐渐升高（P<0.05）,治疗12个月的身高增长（△Ht）、GV 低于治疗 6个月（P<0.05）。治疗6个月、治疗12个月的GV 均与初始治疗时的生活年龄（CA）、骨龄（BA）、身高、体重及垂体高度呈负相关（P<0.05）。将治疗12个月GV 作为因变量,治疗前初始身高（X1）、治疗6个月GV（X2）被纳入方程建立预测模型：Y=7.631-0.035X1+0.567X2,R²=0.791,并通过内外部验证。结论：rhGH治疗对ISS患儿的身高增长具有良好效果,前6个月的效果更好。rhGH治疗后ISS患儿的GV与治疗前CA、BA、身高、体重及垂体高度呈负相关。治疗前的身高、治疗6个月的GV能够较好地预测治疗12个月的GV。     

G1阻滞中p21-E2F间的相互作用

前列腺素A2(PGA2)具有强的体内、外抗增殖活性,引起细胞周期阻滞,同时,可诱导cdk抑制物p21蛋白的表达,后者亦可介导多种细胞的G1阻滞.提示p21^waf1/cip1在PGA2诱导的细胞周期阻滞中具有重要作用.主要介绍了近两年来有关p21^waf1/cip1与转录因子E2F间的相互作用的研究,阐述p21^waf1/cip1在PGA2介导的细胞周期阻滞中的作用机制.     

多囊卵巢综合征患者血清IMA、HIF1α、Vaspin、IGF-1水平与性激素、糖脂代谢及胰岛素抵抗的关系研究

摘要 目的：探讨多囊卵巢综合征（PCOS）患者血清缺血修饰白蛋白（IMA）、缺氧诱导因子1α（HIF1α）、内脏脂肪特异性丝氨酸蛋白酶抑制剂（Vaspin）、胰岛素样生长因子-1（IGF-1）水平与性激素、糖脂代谢及胰岛素抵抗的相关性。方法：选择2017年1月至2019年12月我院收治的268例PCOS患者（PCOS组）,根据体质量指数（BMI）将PCOS患者分为超重/肥胖组（BMI≥24 kg/m²,161例）和正常体重组（18.5 kg/m2≤BMI＜24 kg/m²,107例）,另选择135例于妇科门诊体检的健康女性志愿者为对照组。检测血清IMA、HIF1α、Vaspin、IGF-1水平以及性激素、糖脂代谢、胰岛素抵抗指标,Pearson相关性分析其相关性。结果：PCOS组血清IMA、HIF1α、Vaspin、IGF-1、睾酮（T）、促黄体生成素(LH)、促卵泡激素（FSH）、总胆固醇（TC）、低密度脂蛋白胆固醇（LDL-C）、空腹血糖（FPG）、餐后2小时血糖（2hPG）、空腹胰岛素（FINS）水平,胰岛素抵抗指数（HOMA-IR）均高于对照组（P＜0.001）。PCOS患者超重/肥胖组血清IMA、HIF1α、Vaspin、IGF-1、T、TC、LDL-C、FPG、FINS、2hPG水平,HOMA-IR均高于正常体重组（P＜0.001）。PCOS患者血清IMA、HIF1α水平与T、HOMA-IR呈正相关（P＜0.05）,血清Vaspin、IGF-1水平与TC、LDL-C、FPG、FINS、2hPG 、HOMA-IR呈正相关（P＜0.05）。结论：PCOS患者血清IMA、HIF-1α、Vaspin、IGF-1水平均升高,IMA、HIF-1α、Vaspin、IGF-1均与PCOS胰岛素抵抗有关。     

一氧化氮和氧自由基诱导缺氧再给氧心肌细胞凋亡的bcl-2和p53信号通路研究

观察了心肌缺氧再给氧损伤的一氧化氮(nitric oxide, NO)和氧自由基机制. 新生Wistar大鼠心肌细胞置于95% N₂ /5% CO₂环境培养24 h, 然后置于95% O₂ /5% CO₂环境培养4 h造成缺氧再给氧心肌细胞损伤模型. 单纯缺氧组心肌细胞置于95% N₂/5% CO₂环境培养24 h, 但不再给氧. NO供体硝普钠(SNP, 5 mmol/L)、NO合酶抑制剂Nw-硝基-L-精氨酸甲酯(L-NAME, 100 mmol/L)和其异构体Nw-硝基-D-精氨酸甲酯(D-NAME, 100 mmol/L)以及超氧化物歧化酶/过氧化氢酶(SOD/CAT, 各100 U/mL)分别于缺氧前加入培养基. 正常对照组心肌细胞置于95% 空气/5% CO₂环境下培养. 结果显示, 缺氧24 h能增加培养介质中NO, 硫代巴比妥酸反应产物(TBARS)和乳酸脱氢酶(LDH)水平, 再给氧降低培养介质中NO和 水平, 增加TBARS和LDH水平. 缺氧上调bcl-2和p53和p21/waf1/cip1蛋白表达水平, 而再给氧下调bcl-2蛋白表达水平, 上调p53和p21/waf1/cip1蛋白表达水平. 同时, 缺氧增加心肌细胞凋亡率, 而再给氧增加心肌细胞坏死率. NO供体硝普钠(SNP)增加培养介质中 和TBARS水平, 下调bcl-2蛋白表达而上调p53和p21/waf1/cip1蛋白表达水平, 增加DNA断裂、凋亡及坏死细胞率. L-NAME和 SOD/CAT分别降低培养介质中 和TBARS水平, 它们均能上调bcl-2蛋白表达而下调p53和p21/waf1/cip1蛋白表达水平, 抑制DNA断裂、凋亡及坏死细胞率, 而D-NAME则无此作用. 以上结果表明, 在缺氧再给氧所致心肌细胞死亡过程中, NO和氧自由基参与下调bcl-2蛋白表达水平和上调p53和p21/waf1/cip1蛋白表达水平, 相应地激发细胞凋亡程序, 并提示一氧化氮及氧自由基诱导心肌细胞凋亡的机制与调节 bcl-2和p53和p21/waf1/cip1信号通路有关.     

滋水清肝饮联合甲巯咪唑治疗甲状腺功能亢进症患者疗效观察和血清IGF-1、APN的影响

摘要 目的：评价滋水清肝饮联合甲巯咪唑治疗甲状腺功能亢进症（甲亢）患者临床疗效以及对血清IGF-1、APN水平的影响。方法：选入我院2021年3月~2023年2月收治的甲亢患者80例,随机分为对照组和观察组,各40例,其中对照组予以甲巯咪唑治疗,观察组采用滋水清肝饮+甲巯咪唑治疗。评价并比较两组的临床疗效、血清IGF-1和APN水平变化等。结果：与治疗前相比,两组治疗后主要中医证候积分、心率、FT3和FT4显著降低, TSH明显升高（P＜0.05）,而观察组降低/升高幅度更大,与对照组差异显著（P＜0.05）;观察组治疗总有效率92.50%,显著高于对照组的72.50%（P＜0.05）;与两组治疗前相比,治疗后血清IGF-1和APN水平下降,且观察组下降幅度较对照组大（P＜0.05）;观察组不良反应发生率较对照组低（5.00% vs 25.00%,P＜0.05）。结论：滋水清肝饮联合甲巯咪唑疗效确切,改善临床症状、甲状腺功能,下调血清IGF-1、APN水平,减少不良反应。     

血清cTnI、CK-MB及IGF-1在新生儿高胆红素血症中的变化及临床意义

摘要 目的：分析血清肌钙蛋白T( troponin T,cTnT)、肌酸激酶同工酶(creatine kinase isoenzyme,CK-MB)及胰岛素样生长因子-1(insulin-like growth factor-1,IGF-1)在新生儿高胆红素血症中变化及临床价值。方法：选择2015年1月至2019年12月我院新生儿科收治的80例新生儿高胆红素血症足月新生儿(观察组)以及80例非胆红素足月新生儿(对照组)为研究对象。收集住院资料,包括所有患儿的胎龄、日龄、出生体重、血清总胆红素（total bilirubin,TBIL）、CK-MB、cTnT、IGF-1、头颅核磁共振(skull magnetic resonance,MRI)、临床表现等及出院后随访资料。根据胆红素水平高低,将观察组分为轻度(33例)、中度组(27例)及重度组(20例),比较其：TBIL、IGF-1、CK-MB、cTnT水平。结果：各组新生儿TBIL、CK-MB、cTnT水平比较差异具有统计学意义(P＜0.05)。重度黄疸组TBIL、CK-MB、cTnT值分别高于轻度、中度黄疸组和对照组,IGF-1低于轻度、中度黄疸组和对照组(P＜0.05);中度黄疸组TBIL、CK-MB、cTnT高于轻度黄疸组和对照组,IGF-1低于轻度黄疸组和对照组(P＜0.05);轻度黄疸组TBIL、CK-MB、cTnT高于对照组,IGF-1低于对照组(P＜0.05)。血清cTnT与TBIL水平呈正相关(r=0.587,P＜0.05);血清CK-MB与TBIL水平无明显相关性(r=0.220,P＞0.05);血清IGF-1与TBIL水平呈负相关（r=-0.568,P＜0.05）。苍白球异常信号组患儿血清IGF-1值为(11.05±0.51) ng/mL,明显低于苍白球正常信号组(14.22±2.67) ng/mL(P＜0.05);苍白球异常信号组患儿血清TBIL水平为(347.62±33.01)μmol/L与苍白球正常信号组(341.75±35.14)μmol/L无明显差别(P＞0.05)。结论：检测血清cTnT和IGF-1水平分别有助于预测新生儿高胆红素血症心肌损伤和脑病的发生。     

紫癜性肾炎患儿血清Gd-IgA1、sFlt-1、IgA/C3比值与肾损伤和疗效的关系研究

摘要 目的：探讨紫癜性肾炎（HSPN）患儿血清半乳糖缺陷免疫球蛋白A1（Gd-IgA1）、可溶性fms-样酪氨酸激酶受体l（sFlt-1）、免疫球蛋白A（IgA）/补体C3（C3）比值与肾损伤和疗效的关系。方法：选取成都大学附属医院2019年12月至2021年12月确诊为HSPN的151例患儿作为病例组。另选取同期体检健康的志愿儿童100例作为对照组。对比两组血清Gd-IgA1、sFlt-1、IgA/C3比值、肾功能指标[尿素氮（BUN）、血肌酐（Scr）、24 h尿蛋白（UP）定量（24hUPE）和UP/Scr]。采用Pearson法分析血清Gd-IgA1、sFlt-1、IgA/C3比值与肾功能指标的相关性。对比不同肾脏病理分级和不同疗效患儿的血清Gd-IgA1、sFlt-1、IgA/C3比值。结果：病例组的Gd-IgA1、sFlt-1、IgA/C3比值、BUN、Scr、24hUPE、UP/Scr均高于对照组（P<0.05）。Pearson相关性分析结果显示：Gd-IgA1、sFlt-1、IgA/C3比值与BUN、Scr、24hUPE、UP/Scr均呈正相关（P<0.05）。随着肾脏病理分级的升高，HSPN患儿的血清Gd-IgA1、sFlt-1、IgA/C3比值不断升高（P<0.05）。无效组的Gd-IgA1、sFlt-1、IgA/C3比值高于有效组（P<0.05）。结论：Gd-IgA1、sFlt-1、IgA/C3比值升高参与了HSPN患儿的疾病进展，可导致肾损伤，加重肾脏病理改变，临床可根据上述指标变化指导治疗。     

乳腺癌中Rho A蛋白表达及其与Cyclin D1和P21WAF1/CIP1蛋白表达的相关性

目的探讨Rho A蛋白在人乳腺癌中的表达情况,Rho A蛋白与临床病理因素的关系,及其与细胞周期蛋白Cyclin D1,细胞周期抑制蛋白 P21 WAF1/CIP1表达的相关性.方法应用免疫组化S-P法,检测64例乳腺癌组织及20例正常乳腺组织中Rho A蛋白、Cyclin D1和P21 WAF1/CIP1蛋白的表达情况.结果 (1)Rho A、 Cyclin D1和P21 WAF1/CIP1蛋白在正常乳腺组织中的表达率分别为5.00%、25.00%、15.00%,在乳腺癌组织中的表达率分别为73.44%、59.38%、48.44%,三者在乳腺癌组织中的阳性表达分别与正常乳腺组织相比,均差异有显著性意义(P< 0.01).(2)Rho A蛋白表达与病理组织分级,淋巴结转移相关(P< 0.05),与患者年龄、肿瘤大小及临床分期无关.(3)RhoA蛋白与P21 WAF1/CIP1蛋白表达呈负相关(χ2=4.548,P<0.05),与Cyclin D1蛋白表达无关.结论乳腺癌患者RhoA蛋白过表达与预后不良有关.RhoA蛋白通过下调P21 WAF1/CIP1蛋白参与细胞周期调节,进而与乳腺癌发展及侵袭转移相关.     

MDM2 promotes p21waf1/cip1 proteasomal turnover independently of ubiquitylation

The CDK inhibitor p21waf1/cip1 is degraded by a ubiquitin-independent proteolytic pathway. Here, we show that MDM2 mediates this degradation process. Overexpression of wild-type or ring finger-deleted, but not nuclear localization signal (NLS)-deleted, MDM2 decreased p21waf1/cip1 levels without ubiquitylating this protein and affecting its mRNA level in p53(-/-) cells. This decrease was reversed by the proteasome inhibitors MG132 and lactacystin, by p19(arf), and by small interfering RNA (siRNA) against MDM2. p21waf1/cip1 bound to MDM2 in vitro and in cells. The p21waf1/cip1-binding-defective mutant of MDM2 was unable to degrade p21waf1/cip1. MDM2 shortened the half-life of both exogenous and endogenous p21waf1/cip1 by 50% and led to the degradation of its lysine-free mutant. Consequently, MDM2 suppressed p21waf1/cip1-induced cell growth arrest of human p53(-/-) and p53(-/-)/Rb(-/-)cells. These results demonstrate that MDM2 directly inhibits p21waf1/cip1 function by reducing p21waf1/cip1 stability in a ubiquitin-independent fashion.     

CARM1 regulates proliferation of PC12 cells by methylating HuD

HuD is an RNA-binding protein that has been shown to induce neuronal differentiation by stabilizing labile mRNAs carrying AU-rich instability elements. Here, we show a novel mechanism of arginine methylation of HuD by coactivator-associated arginine methyltransferase 1 (CARM1) that affected mRNA turnover of p21^cip1/waf1 mRNA in PC12 cells. CARM1 specifically methylated HuD in vitro and in vivo and colocalized with HuD in the cytoplasm. Inhibition of HuD methylation by CARM1 knockdown elongated the p21^cip1/waf1 mRNA half-life and resulted in a slow growth rate and robust neuritogenesis in response to nerve growth factor (NGF). Methylation-resistant HuD bound more p21^cip1/waf1 mRNA than did the wild type, and its overexpression upregulated p21^cip1/waf1 protein expression. These results suggested that CARM1-methylated HuD maintains PC12 cells in the proliferative state by committing p21^cip1/waf1 mRNA to its decay system. Since the methylated population of HuD was reduced in NGF-treated PC12 cells, downregulation of HuD methylation is a possible pathway through which NGF induces differentiation of PC12 cells.     

Roles for p21waf1/cip1 and p27kip1 during the adaptation response to massive intestinal resection

The magnitude of gut adaptation is a decisive factor in determining whether patients are able to live independent of parenteral nutrition after massive small bowel loss. We previously established that the cyclin-dependent kinase inhibitor (CDKI) p21(waf1/cip1) is necessary for enterocyte proliferation and a normal adaptation response. In the present study, we have further elucidated the role of this CDKI in the context of p27(kip1), another member of the Cip/Kip CDKI family. Small bowel resections (SBRs) or sham operations were performed in control (C57/BL6), p21(waf1/cip1)-null, p27(kip1)-null, and p21(waf1/cip1)/p27(kip1) double-null mice. Morphological (villus height/crypt depth) alterations in the mucosa, the kinetics of enterocyte turnover (rates of enterocyte proliferation and apoptosis), and the protein expression of various cell cycle-regulatory proteins were recorded at various postoperative times. Enterocyte compartment-specific mRNA expression was investigated using laser capture microdissection. Resection-induced adaptation in control mice coincided with increased protein expression of p21(waf1/cip1) and decreased p27(kip1) within 3 days postoperatively. Identical changes in mRNA expression were detected in crypt but not in villus enterocytes. Adaptation occurred normally in control and p27(kip1)-null mice; however, mice deficient in both p21(waf1/cip1) and p27(kip1) failed to increase baseline rates of enterocyte proliferation and adaptation. The expression of p21(waf1/cip1) protein and mRNA in the proliferative crypt compartment is necessary for resection-induced enterocyte proliferation and adaptation. The finding that deficient expression of p27(kip1) does not affect adaptation suggests that these similar CDKI family members display distinctive cellular functions during the complex process of intestinal adaptation.     

The cyclin-dependent kinase inhibitor p21CIP/WAF is a positive regulator of insulin-like growth factor I-induced cell proliferation in MCF-7 human breast cancer cells

To study the role of IGF-I receptor signaling on cell cycle events we utilized MCF-7 breast cancer cells. IGF-I at physiological concentrations increased the level of p21CIP/WAF mRNA after 4has well as protein after 8hby 10- and 6-fold, respectively, in MCF-7 cells. This IGF-1 effect was reduced by 50% in MCF-7-derived cells (SX13), which exhibit a 50% reduction in IGF-1R expression, demonstrating that IGF-1 receptor activation was involved in this process. Preincubation with the ERK1/2 inhibitor U0126 significantly reduced the IGF-1 effect on the amount of p21CIP/WAF protein in MCF-7 cells. These results were confirmed by the expression of a dominant negative construct for MEK-1 suggesting that the increase of the abundance of p21CIP/WAF in response to IGF-1 occurs via the ERK1/2 mitogen-activated protein kinase pathway. Using an antisense strategy, we demonstrated that abolition of p21CIP/WAF expression decreased by 2-fold the IGF-1 effect on cell proliferation in MCF-7. This latter result is explained by a delay in G1 to S cell cycle progression due partly to a reduction in the activation of some components of cell cycle including the induction of cyclin D1 expression in response to IGF-1. MCF-7 cells transiently overexpressing p21 showed increased basal and IGF-I-induced thymidine incorporation. Taken together, these results define p21CIP/WAF as a positive regulator in the cell proliferation induced by IGF-1 in MCF-7 cells.     

The antiproliferative effect of beta-carotene requires p21waf1/cip1 in normal human fibroblasts.

In normal human fibroblasts, beta-carotene induces a cell-cycle delay in the G1 phase independent of its provitamin A activity via a mechanism not yet elucidated. In this study we provide biochemical evidence showing that delayed progression through the G1 phase occurs concomitantly with: an increase in both nuclear-bound and total p21waf1/cip1 protein levels; an increase in the amount of p21waf1/cip1 associated with cdk4; the inhibition of cyclin D1-associated cdk4 kinase activity; and a reduction in the levels of hyperphosphorylated forms of retinoblastoma protein, and particularly, in phosphorylated Ser780. The role of p21waf1/cip1 in the antiproliferative effect of the carotenoid was further supported by genetic evidence that neither changes in cell-cycle progression nor in the phosphorylation status of retinoblastoma protein were observed in p21waf1/cip1-deficient human fibroblasts treated with beta-carotene. These results clearly demonstrate that p21waf1/cip1 is involved directly in the molecular pathway by which beta-carotene inhibits cell-cycle progression.