Similarly, cells derived from PTP1B KO mice also show defects in cell spreading.16 These data suggest that PTP1B is an important regulator of integrin signaling pathways thereby indicating a role in adhesion, spreading and formation of focal adhesion.17 Developmental events underlying branching morphogenesis in the breast are closely related to pathways important for cancer progression, that is, epithelial plasticity and epithelial–mesenchymal transition (EMT). The gene discussed is PTPN1; the disease is cancer.