MUC5AC and asthma: Another dimension is that after stimulating neutrophil elastase (NE) generated by neutrophils, ezrin, and Sec3 are recruited to the cytoplasmic membrane, and with the participation of PIP2, induces robust mucin 5 AC (MUC5AC) protein secretion [105], leading to increased mucus secretion, which further aggravates asthma (Figure 2).