The anti-apoptotic Bcl-2 proteins (Bcl-2, Bcl-xL, Bcl-w, and Mcl-1) restrain pro-apoptotic proteins (Bax, Bak), thus preserving mitochondrial outer membrane integrity, preventing release of pro-apoptotic proteins, thereby inhibiting apoptosis. Bcl-2 is overexpressed in breast cancers (~75%) [174]. This evidence concerns the gene BCL2 and breast cancer.