MAPK8 and asthma: These findings imply that EV‐packaged let‐7i‐5p derived from PM2.5‐treated HBE cells may inhibit DUSP1 expression to increase the phosphorylation of JNK, ERK and p38, thereby activating the MAPK signaling pathway and inducing asthma attacks through both “horizontal” and “longitudinal” mechanisms.