<n0:ComplexDefinition xmlns:n0="http://ncicb.nci.nih.gov/xml/owl/EVS/ComplexProperties.xsd#"><n0:def-definition>A tetradecapeptide originally obtained from the skins of toads Bombina bombina and B. variegata. It is also an endogenous neurotransmitter in many animals including mammals. Bombesin affects vascular and other smooth muscle, gastric secretion, and renal circulation and function.</n0:def-definition><n0:def-source>MSH2002_06_01</n0:def-source></n0:ComplexDefinition><n0:ComplexDefinition xmlns:n0="http://ncicb.nci.nih.gov/xml/owl/EVS/ComplexProperties.xsd#"><n0:def-definition>A peptide (small protein) found in the brain, gastrointestinal tract, and lungs. It causes the release of certain hormones and enzymes. It also causes smooth muscles to contract. Bombesin is found at high levels on small cell lung cancer cells and on other types of cancer cells. It is a type of neuropeptide and a type of hormone.</n0:def-definition><n0:def-source>NCI-GLOSS</n0:def-source></n0:ComplexDefinition>