Conversely, BRCA1 exerts tumor-suppressive effects via dual mechanisms: (1) upregulating E-cadherin to preserve epithelial integrity, and (2) concurrently suppressing mesenchymal markers (vimentin, PDGFRβ, p-PKCα, TWIST, ZEB1), effectively inhibiting dedifferentiation and reducing invasive potential (57). The gene discussed is CDH1; the disease is neoplasm.