Enzastaurin inhibits the effect of PMA on TRAIL-induced apoptosis. A, after a 5-min pretreatment with 20 nm PMA or diluent (0.04% ethanol) and 10 μm enzastaurin (Enz) or diluent (0.02% DMSO), Jurkat cells were treated for 6 h with 3 ng/ml TRAIL, stained with PI, and analyzed by flow microfluorimetry. B, results from samples in A and additional samples from the same experiment. C, after a 5-min pretreatment with 20 nm PMA or diluent and the indicated concentration of enzastaurin or diluent, Jurkat cells were treated for 4 h with 6 ng/ml TRAIL, stained with PI, and analyzed by flow microfluorimetry. Error bars, ± S.D. of three independent experiments. D, after a 5-min pretreatment with 20 nm PMA or diluent (0.04% ethanol) and 10 μm enzastaurin or diluent (0.02% DMSO), HL-60 cells were treated for 4 h with the indicated concentration of TRAIL, stained with PI, and analyzed by flow microfluorimetry. E, after a 5-min pretreatment with 2 nm PMA or diluent and 10 μm enzastaurin or diluent, HL-60 cells were treated for 4 h with 25 ng/ml TRAIL, washed, diluted into 0.3% agar, and allowed to form colonies. Error bars, ± S.D. of quadruplicate samples.