The PH domain of P-REX2, but not P-REX1, inhibits PTEN produced in mammalian cells. (A) Lysates from HEK293 cells coexpressing PTEN-V5 with empty vector, PH-V5, or P-REX2ΔDHPH-V5 were incubated with V5-agarose beads. Phosphatase assays were then performed on the immunoprecipitated protein. Levels of free phosphate are shown. ±SD, n = 3, **P < 0.01. (B) Lysates from HEK293 cells expressing PTEN-V5 with empty vector, P-REX2-PH-V5, or P-REX1-PH-V5 were incubated with V5-agarose beads, and phosphatase assays were performed on immunoprecipitated proteins. Levels of free phosphate released are shown. ±SD, n = 3, **P < 0.01.