The Bcl-2 family of cytoplasmic proteins are major regulators of programmed cell death. This process of cellular suicide, termed apoptosis, is thought to be conserved among all multicellular organisms. Apoptosis is vital for normal development, maintenance of tissue homeostasis, and proper immune function; disturbances in it are implicated in many disorders including cancer, degenerative diseases, and autoimmune disorders. Members of the Bcl-2 family, some of which work in opposition to the others, determine whether a cell undergoes apoptosis.