Effects of PKC412, imatinib, AMN107, and 2CdA on MCL-1 protein expression and cell viability in neoplastic mast cells. Effects of PKC412 (A, E), AMN107 (B, F), imatinib (STI571) (C, G), or 2CdA (D, H) on MCL-1 protein expression (upper panel) and on cell viability (lower panel) in HMC-1.1 cells lacking KIT D816V (A-D) and in HMC-1.2 cells exhibiting KIT D816V (E-H). MCL-1 protein expression was determined by Western blotting using a polyclonal anti–MCL-1 antibody. Equal loading was confirmed by probing for β-actin. Cell viability was analyzed by recording the percentage of apoptotic cells. Results documenting drug effects on cell viability represent the mean ± SD from 3 independent experiments.