Fig. 8. Lack of proliferation potential following silencing of CK2α results in up-regulation of p27^KIP1, which protects cells in circumstances sub-optimal for cell growth. (A) Cells were transfected with siRNA directed against p27^KIP1 mRNA 24 hours after plating in the presence or absence of doxycycline for inducing CK2α down-regulation. Cells were synchronized by serum withdrawal and harvested 48 hours afterward. It followed their analysis by flow cytometry. Sub-G1 denotes cells with fragmented DNA indicative of induction of cell death. Experiments were repeated four times. Average values are expressed in percentage +/- STDEV. *P = 0.0255, **P = 0.0007, ***P = 0.0054. (B) Twenty-four hours after plating in 6-well plates in the presence or absence of doxycycline, cells were transfected with scrambled or p27^KIP1 siRNA. Cells were subsequently treated as shown in the Fig.. (C) 12 hours after serum withdrawal cell growth was analyzed by the IncuCyte S3 live-cell system (i.e. starting of the measurements). Measurements were performed every three hours. Cell pictures shown in the Fig. are representative and were taken at the end of the experiment. Data represent mean values +/- STDEV of n = 3 experiments, *P<0.0001.