Stimulation of division of sparse and confluent 3T3 cell populations by a fibroblast growth factor, dexamethasone, and insulin.

The stimulation of division of Balb/c 3T3 mouse fibroblasts by fibroblast growth factor alone and in combination with insulin and a glucocorticoid (dexamethasone) has been investigated. Fibroblast growth factor stimulates DNA synthesis in sparse, quiescent cultures maintained in a low serum concentration, but does not support more than two division cycles. In the presence of dexamethasone, the growth factor supports continuous division cycles. The addition of insulin significantly augments the response to fibroblast growth factor alone and slightly augments the response to growth factor plus dexamethasone. Fibroblast growth factor stimulates the division of confluent, quiescent cultures grown in 10% serum. When growth factor plus dexamethasone is added to such cultures, "contact inhibition" is overcome.