ALOX12 and infection: A 12-lipoxygenase inhibitor (CDC), known to interfere with PAO1-induced neutrophil trans-epithelial migration had no effect on pepsin-induced neutrophil trans-epithelial migration (Fig. 3D), suggesting that pepsin at pH 3 triggers neutrophil trans-epithelial migration through a distinct mechanism than infection at neutral pH15,19,20.