(MCL-1 + BFL-1)/BCL-2 provides the most significant linear correlation for sensitivity to ABT-737. Cell viability after ABT-737 treatment was plotted against: (A) (MCL-1 + BFL-1)/BCL-2, (B) MCL-1/BCL-2, (C) BFL-1/BCL-2, (D) BCL-B/BCL-2, (E) (MCL-1 + BFL-1 + BCL-B)/BCL-2, and (F) (MCL-1 + BFL-1)/(BCL2 + BCL-XL) ratios. Spearman correlation (r) and P values are shown.