Fig. 2. PI3K signaling mediates specific expression of HIF-1 induced by insulin. PC-3 (A) and DU145 (B) cells were cultured without serum for 24 h. The PI3K-specific inhibitors LY294002 and wortmannin at the indicated concentrations were added 30 min before the addition of insulin. The cells were incubated in the presence (+) or absence (-) of insulin for 6 h. Nuclear extracts were prepared and used to analyze HIF-1 and HIF-1ß protein expression. The exposure times for immunoblots A and B were different, and the signals on these two blots are not comparable.