Conditional suppression of p21 enhances proliferation of WT NPC.

<p><b>A</b>) One thousand WT NPC cells were kept in proliferating conditions for 4 days. Cells were cultured in 24-well plates in triplicates. The mean number of cells at the time of collection; <b>B</b>) Cells were fixed and stained for Ki67 or p21 . The graph depicts the percentage of p21- or Ki67-positive cells in each culture. Counting was performed in triplicates (>500 cells per sample). Data are presented as a mean ± SEM, *, p<0.05. Two independent experiments were conducted, and representative results are shown; <b>C</b>) Representative confocal images of NPC treated with either control lentivirus (control) or lentivirus expressing p21 shRNA. The cells were stained for Ki67 (intranucelar, red) and p21 (intranuclear, green). Note the increased number of Ki67-positive and the decreased number of p21-positive cells after p21 shRNa treatment.