PTEN and prostate carcinoma: While PTEN was initially identified as a TGF-β-regulated and epithelial cell-enriched phosphatase (TEP1) [100], this concept was challenged by Kimbrough-Allah et al. [101], who reported that, in prostate cancer cells, TGF-β increased the protein level of PTEN, but had no effect on the PTEN mRNA expression level.