CFTR and cystic fibrosis: In the colon, on the other hand, as Cftr is not involved in regulation of baseline mucus formation, and that parallel activation of Ca2+ and cAMP-mediated pathways restore Ca2+ mediated mucus release from the colonic crypts, may allow for the formation of a mucus layer that protects the epithelium from the microbiota, thus explaining the less severe pathology in CF colon [17].