Resting-proliferative transition in cultured mammalian cells.

Cell lines established in culture have been tested for their ability to enter a resting state upon serum step-down. The reentry of resting cells into a proliferative state has been studied. This transition between states of resting and of proliferation is considered a manifestation in cell cultures of physiologic growth regulatory mechanisms. The regulatory effects of hormones and hormone-like peptide growth factors on the resting-proliferative transition are analyzed.