Relevant to the pathogenesis of COPD, activating transcription factor 4 (ATF4)-mediated endoplasmic reticulum stress (ER stress) has been suggested to be a key regulator for COPD-relevant airway epithelial gene expression [30], and ATF4 is a validated target of miR-214 [31]. The gene discussed is ATF4; the disease is chronic obstructive pulmonary disease.