Decreased content of the 35 kDa cytoskeletal protein p35 in Friend erythroleukemia cells exposed to dimethyl sulfoxide and retinoic acid is associated with entrance into a quiescent substrate

1. The effect of all-trans-retinoic acid (RA) on cell cycle kinetics, RNA content, and expression of the 35 kDa cytoskeletal protein p35 in exponentially-growing Friend erythroleukemia (FL) cells was compared with the prototypic differentiation-inducer dimethylsulfoxide (DMSO). 2. Two G1 phase populations of RA-treated FL cells were identified: one with an intermediate RNA content (T-cells) similar to G1 cells in near-plateau-phase control cultures and the other with a very low RNA content (Q-cells) similar to DMSO-differentiated cells; although quiescent, RA-treated cells remained undifferentiated as evidenced by the absence of late-stage markers of erythroid maturation. 3. Decreases in the cellular content of p35 occurred in both DMSO- and RA-treated FL cells, correlating with the onset of accumulation of cells into G1, and stabilized by 48 hr after initial exposure to either inducer. 4. Down-regulation in the cellular p35 content, thus, appears to be linked to entrance of FL cells into a quiescent substrate and independent of the subsequent capacity for erythroid differentiation.