FIGURE 8.
Coexpression of st and cyclin E in density-arrested cells endows NHF with unrestrained proliferation and foci formation properties, and PP2A inactivation is important for these effects. BJ-hTERT fibroblasts were grown to high density and transduced with indicated adenoviruses. A, cells were harvested and counted at the indicated time points. B, cyclin E and st induced foci formation and continued DNA synthesis 18 days post-transduction as observed by detection of BrdUrd incorporation and DNA staining with 4′,6-diamidino-2-phenylindole (DAPI). (Viral infection was repeated weekly to avoid loss of episomal exogenous DNA.) C and D, stable BJ-hTERT-Cyc E cells were transduced with the indicated retroviruses. C, 200,000 cells were seeded in 6-well plates and counted in triplicate every 24 h. Total cell number is shown. D, levels of retrovirally expressed st proteins were determined by Western blot analysis 3 days postinfection. E, wild type and mutant st proteins were immunoprecipitated from normalized protein extracts containing comparable levels of st or st97,102. Immunoprecipitations (IP) were resolved by SDS-PAGE. PP2A/A and PP2A/C were detected by Western blot analysis (WB).