FIG. 1.

Retardation of cell cycle reentry by Bcl-2 is independent of pRB. Quiescent (A) wt or (B) RB^−/− fibroblasts were stimulated to reenter the cell cycle with 10% FBS, and their cell cycle distribution was analyzed at the indicated times by DNA content. The data represent the percentage of cells in S and G₂/M phases relative to all cells with ≥2N DNA content for the untransfected parental cell line and independent clonal derivatives stably transfected with the empty vector (puro) or the bcl-2 expression vector. The results are representative of three similar experiments performed for each genotype.