FIGURE 4.

cdc6 mRNA expression is potently up-regulated by st in serum-starved and density-arrested BJ-hTERT cells. A, BJ-hTERT cells were grown to high density and transduced with 40 MOI of adenovirus expressing st and/or control EGFP and harvested 30 h later. Exponentially growing cells were used as controls. Levels of expression of indicated mRNAs were analyzed by Northern blot as described under “Experimental Procedures.” Radioactive signals were measured by densitometry, quantified with NIH Image J, and represented as fold increase. B, BJ-hTERT fibroblasts were synchronized by serum starvation for 72 h, re-stimulated with 10% FBS and harvested at indicated time points for Northern blot analysis as in A. C, BJ-hTERT cells were grown to high density, transduced with adenovirus expressing st and harvested at indicated time points after transduction and treated as in A. D, BJ-hTERT cells were serum-starved for 72 h, transduced with adenovirus expressing st and harvested at indicated time points after transduction and treated as in A.