In murine breast cancer models expressing mammary-specific ErbB2/neu oncogene, loss of Pten in stromal fibroblasts via the mesenchymal-specific Fsp-Cre transgene, accelerated initiation, progression and malignant transformation of neu oncogene-driven mammary epithelial tumours, associated with extracellular matrix (ECM) remodelling, innate immune cell infiltration, and increased angiogenesis [47]. The gene discussed is PTEN; the disease is breast carcinoma.