Bcl-2-like protein 1 (BCL2L1), is also known as Apoptosis regulator Bcl-X (Bcl-XL). BCL2L1 / Bcl-XL is a homodimer protein and belongs to the Bcl-2 family. BCL2L1 is expressed at high levels in cells that undergo a high rate of turnover, such as developing lymphocytes. BCL2L1 is a potent inhibitor of cell death. BCL2L1 Inhibits activation of caspases. BCL2L1 appears to regulate cell death by blocking the voltage-dependent anion channel (VDAC) by binding to it and preventing the release of the caspase activator, CYC1, from the mitochondrial membrane. BCL2L1 / Bcl-XL also acts as a regulator of G2 checkpoint and progression to cytokinesis during mitosis.