Sensitization of A204 and A673 cells to doxorubicin- and TRAIL-induced apoptosis by PI3K inhibition. A204 (A) and A673 (B) cells were pretreated or not with 30 μmol/L LY294002 for 1 hour, incubated with doxorubicin (0.1 μg/ml) or TRAIL (100 ng/ml) and cultured under normoxic or hypoxic conditions for up to 72 hours. 24 hours-white bars, 48 hours- black bars, 72 hours-hatched bars. Apoptosis was determined by FACS analysis of DNA fragmentation of propidium iodide–stained nuclei; the percentage of specific apoptosis is shown. Columns, mean of three independent experiments done in duplicate; bars, SD. For statistical analysis two-way ANOVA was performed comparing specific apoptosis of either TRAIL or doxorubicin-induced apoptosis under normoxia vs hypoxia (*p < 0.05, **p < 0.01, ***p < 0.001) and hypoxia induced apoptosis vs hypoxia + LY294002 (##p < 0.01, ###p < 0.001) as well as hypoxia + TRAIL or doxorubicin vs hypoxia + LY294002 + TRAIL or doxorubicin (§§p < 0.01, §§§p < 0.001).