Effects of pharmacologic inhibitors on MCL-1 expression in CML cells. (A,B) Primary CML cells (n = 3) were incubated with PD98059 (50 μM), LY294002 (20 μM), rapamycin (20 nM), or control medium (control) for 12 hours. After incubation, RNA was isolated and subjected to Northern blot analysis using an mcl-1-specific cDNA probe. Panel A shows a representative experiment and panel B a densitometric evaluation of mcl-1 mRNA expression (relative to β-actin loading control); results are given as percent of control (untreated cells). (C,D) Western blot analysis of primary CML cells after incubation with inhibitors (same type and dose as in panel A) for 24 hours. Panel C shows a representative experiment and panel D a densitometric evaluation of MCL-1 protein expression (relative to β-actin). Results represent the mean ± SD from the 3 donors and are given as percent of control (ie, untreated cells). (E,F) Western blot analysis (densitometry corrected for β-actin) of MCL-1 expression in K562 cells (E) and KU812 cells (F) after incubation with inhibitors (PD98059, 50 μM; LY294002, 20 μM; rapamycin, 20 nM) or control medium. Results are given as percent of control (ie, untreated cells) and represent the mean ± SD from 3 independent experiments in each cell line; ^*P < .05.