| Abstract: | The presence of mitogenic and morphogenic activity in extracts of bovine salivary (parotid) glands is reported. The crude and partially purified extracts stimulated cultured rat cerebellar cells (astrocytes) and skin fibroblasts to undergo morphogenesis. The incorporation of 3H]thymidine was also stimulated in astrocytes, skin fibroblasts, and established fibroblastic cell lines. Growth-promoting activity was also demonstrated. The expression of maximum mitogenic activity in skin fibroblast cultures, but not kidney fibroblast cultures, required the presence of serum. The biological activity had an apparent native molecular weight greater than 230,000, was heat-sensitive, trypsin-resistant, and slightly sensitive to the action of papain. |
