MCL1 and chronic myelogenous leukemia, BCR-ABL1 positive: We have previously shown that IFNγ upregulated several anti-apoptotic members of the BCL2 and BIRC (baculoviral IAP repeat containing) gene families, including the long isoform of MCL1 (MCL-1L) in the imatinib-treated CML cell line JURL-MK1.