FIG. 3.
Conditional activation of FoxO3a results in downregulation of cyclin D1 and D2 proteins and inhibition of CDK4 activity in human colon carcinoma cells. DL23 and DLD-1 cells were left untreated (0 h) or treated with 100 nM 4-OHT for the indicated time periods. Total lysates were prepared and subsequently analyzed by Western blotting for the presence of cyclin D1 (Cyc D1) (A), or cyclin D2 (Cyc D2) and p27kip1 (B, lower panel). Additionally, total phosphorylation of pRb (ppRb) (B, upper panel) or of phospho-pRb S780 (pS780pRb) (B, lower panel) was determined by using an antibody against total pRb or a phosphospecific antiserum against S780 of the pRb protein, respectively. Equal loading for panels A and B was confirmed by Western blotting for CDK4.