Taken together, our data show that early inactivation of p120 in the context of combined E-cadherin and p53 loss largely prevents formation of mouse ILC, and leads to the formation of high-grade basal mammary tumors that are characterized by a more prominent expression of the basal markers CK14 and vimentin, metaplastic and sarcomatoid histology and strong nuclear atypia. The gene discussed is CCL27; the disease is breast cancer.