May play a role in apoptosis. Isoform 1 seems to be the main initiator. Interacts with MCL1, BCL2, BCL2L1/BCL-Xl, BCL2A1 and BCL2L2/BCL-w. Interacts with the myosin V actin motor complex through its binding to DLC2 (By similarity). Isoform 1 is mainly expressed in B-lymphoid cells. Isoform 2 and isoform 3 are mainly expressed in B-CLL and normal B-cells. Belongs to the Bcl-2 family.