Substance P (SP)/neurokinin-1 receptor (NK1R) may regulate pancreatitis leukotriene B4 (LTB4) production via the MAPK signaling pathway, and LTB4 may regulate neutrophil reverse transendothelial migration (rTEM) in AP, which further promotes AP-ALI [32, 33]. This evidence concerns the gene TACR1 and acute respiratory distress syndrome.