PTEN and neoplasm: The tumor-supporting effect has been shown to result from CAF secretion of various factors including hepatocyte growth factor (HGF), transforming growth factor beta (TGF-β), stromal-derived factor 1 (SDF-1), interleukin 1β (IL-1β), PDGF, phosphatase and tensin homolog (Pten), and Sonic hedgehog (Shh), among others, and activation of their respective receptors [71,82].