The effects of mutations in p53 or Pten onthe mammary epithelium have been documented (Stambolic et al, 2000; Li et al, 2002; Herschkowitz et al, 2012; Knight et al, 2013).The impact of combined inactivation of these tumor suppressors, which frequently occurs in breastcancer, is poorly understood. This evidence concerns the gene PTEN and neoplasm.