Inactivation of PTEN in mouse breast stromal fibroblasts accelerated the malignant transformation of breast epithelial cells, and PTEN knockout in stromal fibroblasts promoted extracellular matrix remodeling, tumor angiogenesis, proliferation, invasion, metastasis, and other events, and mediated therapeutic resistance in mice with breast cancer (30, 31). The gene discussed is PTEN; the disease is neoplasm.