MCL1 and plasma cell myeloma: Figure 1E shows the correlation coefficients of −0.6, 0.34, 0.31, −0.29, −0.21, and 0.76 for BCL2, BCL-xL, MCL1, BIK, BID, and BAD, respectively. These findings indicate a strong negative correlation between ABT199 IC50 values and the level of its target BCL2 protein. These results are consistent with previously published observations on AML, T-ALL and neuroblastoma cell lines [11, 21, 22] but not with our data obtained in cultured myeloma cell lines [12].