FIG. 9.

p21^Waf1/Cip1 upregulation is required for PKC-induced cell cycle progression. (A) Endogenous p21 protein level in the wild-type and empty vector-transfected cells (pREP1 and -4) and in p21 antisense-transfected cells (p21AS); 50 μg of protein was loaded per well. (B) Flow cytometry analysis of pREP1 and p21AS3 clones following PMA treatment. There is a marked reduction in the number of p21AS3 cells induced to progress through G₂/M compared to empty vector-transfected cells (pREP1). For Western blot analysis of the p21 protein (bottom), extracts were collected at the same time as the flow cytometry samples. (C) Flow cytometry analysis of wild-type, empty vector-transfected, and p21 antisense-transfected cells at 6 and 9 h following PMA treatment. p21AS clones exhibit a marked reduction of the number of cells induced to progress through G₂/M. ΔG₂/M = % G₂/M PMA treated − % G₂/M control. Each bar is the mean of three independent experiments; the standard error of the mean for each cell line is plotted on the graph.