Although rats and humans contain one gene encoding for A1/BFL-1, mice contain four genes, three of them encoding for the functional paralogues A1a, A1b and A1d. These three share more than 95% homology at the protein as well as at the DNA level, whereas A1c encodes a pseudogene.12 Because of this complex genetic organization of the Bcl2a1 locus in mice, no functional studies have been performed, leaving the role of A1 in preclinical models of cancer unexplored. Here, BCL2A1 is linked to cancer.