Mitosis of contact-inhibited 3T3 preadipocytes precedes chemically induced differentiation into adipocytes.

We studied the conversion of 3T3 cells into adipocytes in vitro after pulsed exposure of confluent, nongrowing cultures to various combinations of the "triggering" agents, methylisobutylxanthine, dexamethasone, and fetal calf serum. Conversion of nongrowing 3T3 preadipocytes into adipocytes takes place after the cells have been stimulated to undergo one round of cell division. Maximal cell division and cytodifferentiation occur only when all three triggering agents are present.