Human cancer cells are commonly resistant to apoptosis due to the overexpression of anti-apoptotic Bcl-2 family (e.g. Bcl-2, Mcl-1 and Bcl-xL) or alternatively, due to down-regulation of pro-apoptotic BH3-only proteins (e.g. Noxa, Bik or Puma) [152]. This evidence concerns the gene BCL2 and cancer.