BCL2L1 (BCL2 Like 1) is a protein that belongs to the Bcl-2 family and plays a key role in regulating apoptosis, or programmed cell death. By preventing the release of factors that trigger cell death from mitochondria, BCL2L1 supports cell survival and helps maintain cellular health during stress. It is found in many tissues and is involved in disease processes, including cancer, where its overexpression allows cancer cells to resist apoptosis. This resistance is often linked to chemotherapy failure and poorer outcomes in cancer patients.