PTEN and chronic obstructive pulmonary disease: Three pathways in SAE were found to have potential significance in the pathogenesis of COPD, namely phosphatase and tensin homolog (PTEN) signal, NF-E2-related factor 2 (Nrf2) mediated oxidative stress, and interleukin-17F(IL-17F) inflammatory response pathway (Vucic et al., 2014).