APOBEC3 genes: retroviral restriction factors to cancer drivers

•APOBEC3 (A3) enzymes deaminate single-stranded DNA, mutating viral genomes. •Tumors harbor mutations likely due to off-target A3 deamination of chromosomal DNA. •A common APOBEC3 deletion polymorphism increases breast cancer risk. •A growing body of evidence points to a driver role for APOBEC3s in tumorigenesis. The APOBEC3 cytosine deaminases play key roles in innate immunity through their ability to mutagenize viral DNA and restrict viral...