Fig. 5. In PC-3 cells, PTEN inhibits HIF-1 but not HIF-1ß protein expression. PC-3 cells were infected three times with the retroviral expression vector pCR2 alone or carrying the wild-type PTEN insert as described. After infection, the cells were cultured in growth medium for 48 h and then switched to serum-free MEM with Earles salts for 24 h, followed by incubation in the presence or absence of 200 nM insulin for 6 h. HIF-1 and HIF-1ß protein expression was determined by immunoblot analysis.