BIM belongs to the BCL-2 protein family. BCL-2 family members form hetero- or homodimers and act as anti- or pro-apoptotic regulators that are involved in a wide variety of cellular activities. BIM 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. Bim expression and activity are regulated at the transcriptional, translational and post-translational levels; coordinated expression and activity of Bim shape immune responses, and ensure tissue integrity. Cancer cells develop mechanisms that suppress Bim expression, which allows for tumor progression and metastasis.