PTEN and idiopathic pulmonary fibrosis: PTEN protein, as a dual-specificity lipid and protein phosphatase, antagonizes the phosphoinositide 3-kinase (PI3K)-Akt signal pathway and dephosphorylates focal adhesion kinase (FAK), which has been implicated in carcinogenesis and in the pathogenesis of IPF [17, 31, 32].