BCL2L11, also known as Bim, belongs to the BCL-2 protein family. Members of this family form hetero- or homodimers and act as anti- or pro-apoptotic regulators that are involved in a wide variety of cellular activities. BCL2L11 contains a Bcl-2 homology domain 3 (BH3). It has been shown to interact with other members of the BCL-2 protein family, including BCL2, BCL2L1/BCL-X(L), and MCL1, and to act as an apoptotic activator. BCL2L11 gene functions as an essential initiator of apoptosis in thymocyte-negative selection.