Members in the Bcl-2 family are critical regulators of apoptosis by either inhibiting or promoting cell death. Bcl-2 homology 3 (BH3) domain containing pro-apoptotic proteins, such as Bax, Bid, and Bik, form a growing subclass of the Bcl-2 family. Another such protein is the Bcl-2-antagonist of cell death (Bad). Bad regulates apoptosis by forming heterodimers with anti-apoptotic proteins Bcl-2 and Bcl-xL, thereby preventing them from binding with Bax. Bad activity is regulated by its phosphorylation; it is inactivated by kinases such as Akt and MAP kinase and thus promotes cell survival, whereas JNK-induced phosphorylation promotes the apoptotic role of Bad.
