For example, the loss of tumor suppressors, such as TGFBR2 or phosphatase and tensin homolog (PTEN) in prostate and breast fibroblasts, respectively, has been associated with breast and prostate cancer mouse models (Bhowmick et al. 2004, Cheng et al. 2005, Trimboli et al. 2009). The gene discussed is PTEN; the disease is prostate cancer.