The K14cre;Brca1flox/flox;Trp53flox/flox and K14cre;Brca2flox/flox;Trp53flox/flox mice develop mammary tumors with a defect in homologous recombination (HR) due to genetic knockout of Brca1 or Brca2, respectively [22-24]. Here, BRCA2 is linked to breast cancer.