CXCL1 and colitis: Our postulate was prompted by the observation that cathelicidin-deficient mice (Camp−/-), have an exacerbated diarrhea when challenged with either a colitis-inducing chemical or infectious agent (e.g. Clostridium difficile).32,33 Here we examined signal transduction pathways and other mechanisms whereby cathelicidin, in concert with LPS, can upregulate the neutrophil chemokine, CXCL8/CXCL1, contributing to the influx of neutrophils during infectious colitis.