Differential effects of ErPC3 and LY294002 on prostate cancer cell survival and p-Akt levels. (A, B, left panels) DU145, LNCaP, and PC3 cells were treated with solvent controls or 25-100 µM ErPC3 or 25-100 µM LY294002. 48 h later a WST-1 assay was performed to quantify the number of viable cells. PC3 cells were most sensitive to treatment with ErPC3 (A, left panel), whereas LNCaP cell were most susceptible to LY294002-treatment (B, left panel). Western blot analysis of lysates generated from PC3 cells 48 h after treatment with 0-25 µM ErPC3 showed a massive reduction of Akt-phosphorylation at serine 473 (p-Akt) whereas almost no reduction of p-Akt was found 48 h after irradiation with 2 or 10 Gy (A, right panel). ErPC3 also reduced p-Akt levels in LNCaP cells however with lower potency (A, right panel). Western blot analysis of lysates generated 0-48 h after treatment with 50 µM LY294002 showed a massive down-modulation of p-Akt-levels in LNCaP cells within 1 h after treatment; still, a considerable reduction in p-Akt levels could be detected 48 h after treatment. In contrast, LY294002 failed to reduce p-Akt levels in PC3 cells at any time point measured (B, right panel).