MTOR and pulmonary fibrosis: Moreover, the existing research found that metformin exhibited pleiotropic mechanisms for alleviating lung fibrosis, such as NOX4 inhibition (Jarman et al., 2014; Sato et al., 2016), IGF-1 suppression (Xiao et al., 2020), and mTOR inactivation (Shao et al., 2015; Rangarajan et al., 2018), and so on.