MTOR and chronic obstructive pulmonary disease: Some of these pathways were reported to be related to COPD, such as the mTOR signaling pathway (Houssaini et al., 2018), NF-kappa B signaling pathway (Wu et al., 2020), PI3K–Akt signaling pathway (Zhang et al., 2020a), and oxidative phosphorylation (Kim et al., 2015), demonstrating the reliability of the identified DEGs.