Since inactivation of INK4-CDK4/6-RB pathway in mice induces mammary luminal type tumors with little effect on EMT activation 7, 15, 20, 47, p18;Brca1 and p18;Gata3 mutant mice provide us a unique opportunity to investigate and compare the role of Brca1 and Gata3 loss in activation of EMT in breast cancers under a genetically intact p53 background. The gene discussed is CDKN2A; the disease is breast cancer.