Bim, Bcl-2 interacting mediator of cell death, is a pro-apoptotic protein belonging to the Bcl2 family of proteins containing a Bcl2 homology domain 3 (BH3). It is proapoptotic and exerts its effects by interacting with prosurvival members of the Bcl2 family like Bcl2, BclxL and Bclw. Bim is sequestered in an inactive conformation through binding to the microtubule-associated dynein motor complex. Certain apoptotic stimuli release Bim from microtubules, allowing inhibitory binding to anti-apoptotic Bcl-2 family members and subsequent iniation of apoptosis.