Effects of mcl-1-specific siRNA on K562 cells. K562 cells were kept untransfected (control) or were transfected with an mcl-1-specific siRNA (mcl-1-siRNA; 200 nM). An siRNA against luciferase (luc-siRNA) was used as control. (A) Effect of mcl-1-siRNA on expression of MCL-1 protein in K562 cells determined by Western blotting. Equal loading was confirmed by probing for β-actin. (B) Effects of luc-siRNA and mcl-1-siRNA on cell viability determined by recording the percentage (%) of apoptotic cells. Results represent the mean ± SD from 3 independent experiments.