There is a reduction in the phosphatase and tensin homolog-deleted from chromosome 10 (PTEN)-induced putative kinase 1-Parkin-E3 ubiquitin protein ligase (PRKN) pathway-mediated which regulates mitochondrial function in COPD epithelial cells and is associated with increased mitochondrial reactive oxygen species (mROS) production (Mizumura et al, 2014; Araya et al, 2019). The gene discussed is PTEN; the disease is chronic obstructive pulmonary disease.