FIGURE 5.

Effects of Klf4 on RARα-mediated increase in phosphoactive Akt and ERK levels. A, VSMCs were infected with pAd, pAd-Klf4, or pAd-Klf4 plus pCMV-hRARα for 48 h. Serum-starved cells were incubated with vehicle (DMSO) or the RARα agonists Am80 (10 μm) and Am580 (10 μm) for 4 h before harvesting. The cell lysates were immunoblotted with the indicated antibodies. B, pAd- and pAd-Klf4-infected VSMCs were serum-starved for 24 h and then treated with either Am80, the RARα antagonist Ro 41-5253 (20 μm), or the combination Am80 + Ro 41-5253 for 4 h before harvesting. C, pAd- and pAd-Klf4-infected VSMCs were transfected with control (NS) siRNA or rat RARα siRNA and harvested 48 h later. In all experiments, the cells were lysed, and Western blot analysis was carried out with the indicated antibodies. The blots are from representative experiments that have been repeated three times with similar results.