Effects of BPS and 8-Br-cAMP on p27kip1protein expression during hypoxia. Cultured HPASMC were exposed to 21% and 2% oxygen with or without 1 mM of 8-Br-cAMP or 10 μM of BPS for 24 hours, and then Western blotted. Hypoxia decreased p27kip1 protein expression. BPS and 8-Br-cAMP each significantly increased p27kip1 protein expression under both normoxia and hypoxia. Photomicrographs are representative of 4 similar experiments, and bar graphs show density ratios of p27kip1 protein versus those of β-actin bands. Open and solid bars, 21% and 2% oxygen, respectively. Data are expressed as means ± SE (n = 4). *P < 0.05 versus 21% oxygen control. †P < 0.05 versus 2% oxygen.