KMT2A and leukemia: To obtain more insight into why CCI-006 induced a pro-apoptotic UPR in a subset of MLL-r leukemia cells while the unresponsive MLL-r leukemia cells were unaffected, we generated resistant pools from the inherently sensitive MLL-r leukemia PER-485 cells, by subjecting this cell line to multiple rounds of selection in CCI-006 (Fig. 4a).