FIG. 5.

Adhesion stimulates G₁ cell cycle events in primary cells. Adherent primary prostate epithelial cells (A) or primary keratinocytes (B) were serum starved for 24 h, placed in suspension (S), left untreated or treated with 0.5 μM PD168393 (PD), and plated on FN in the absence (FN) or presence (EGF) of 40 ng of EGF/ml for 18 h. Levels of cyclin D1 (cycD1), cyclin A (cycA), p27, p21, and Rb phosphorylation (P-Rb) were monitored by immunoblotting cell lysates with their respective antibodies. Note that the levels of Rb phosphorylation are less than optimal due to the late time point selected for this assay. *, cyclin D1 is the lower band. Total levels of Akt were monitored by immunoblotting as a control for total protein levels in the extracts.