<n0:ComplexDefinition xmlns:n0="http://ncicb.nci.nih.gov/xml/owl/EVS/ComplexProperties.xsd#"><n0:def-definition>Secreted by Vibrio cholerae, Cholera Toxin is a natural bacterial enterotoxin consisting of major components heavy A- and light B peptides (choleragenoid) that initiates a signaling cascade in intestinal epithelial cells causing a dysfunction of chloride channels, loss of water, and diarrhea. B peptide anchors the protein to epithelia; A peptide enters the cytoplasm and activates adenylate cyclase. Due to its cytotoxicity, cholera toxin is being studied for tumor cell targeting and cancer chemotherapy. (NCI04)</n0:def-definition><n0:def-source>NCI</n0:def-source></n0:ComplexDefinition>