Antiapoptotic BCL-2 family mRNA levels in ABT-737 sensitive, intermediate, and resistant CLL groups. RNA expression of antiapoptotic Bcl-2 family members, as determined by quantitative RT-PCR, was normalized to β-actin for each CLL patient sample. BCL-2, MCL-1, and BCL2A1 (BFL-1) levels were more abundant than those of BCL-B, BCL-XL, and BCL-W in primary CLL. (A) The sensitive group. (B) The intermediate group. (C) The resistant group. Mean values are shown.