MCL1 and cancer: Myeloid cell leukemia-1 (MCL-1) is an anti-apoptotic member of the BCL-2 family of proteins that regulates apoptosis.1 Overexpression of MCL-1 is associated with a wide range of human cancers, and protects cancer cells from apoptosis, which inherently also reduces the sensitivity of these cells to standard chemotherapies, as well as to radiotherapy.2–4