MCL1 and mantle cell lymphoma: Indeed, whereas neither BCL2/MCL1 nor BCL2/BCL2XL mRNA ratios were sufficient (Supplementary Fig. S1A), BCL2/(MCL1+BCLXL) mRNA ratio discriminated sensitive from resistant MCL cells with a cut-off value of 0.67 (p < 0.001; Fig. 1B).