Involvement of Bcl-2 and Mcl-1 levels in ABT-737 induced apoptosis. (A-C) Seventy-two hours after, Bcl-2 or Mcl-1 siRNA transfection in myeloma cells as indicated, protein levels were examined by immunoblotting, and cells were treated with ABT-737 for 24 hours. Apoptosis was quantified by Apo 2.7 staining. Results represent the mean of 4 independent experiments. (D) KMM1 were transfected with pRc-CMV Bcl-2 or empty vector for 48 hours before to be cultured with ABT-737 for 24 hours. Results represent the mean of 5 independent experiments. Statistical analysis were performed by paired Student t test: *P < .05; **P < .005; and ***P < .0005.