MAPK3 and chronic obstructive pulmonary disease: The pathogenesis of COPD is complicated and unclear and related to many important pathways, such as MAPK-related signaling pathways, ERK1/2, ERK5, p38, and JNK, which play prominent roles in the regulation of the innate and adaptive immune response (Liu et al., 2007; Pereira and Rodrigues, 2020; Wang et al., 2020).