CCKBR and neoplasm: Interestingly, compared to CCK2R-HEK293-xenografted mice, the CCK2Ri4sv-HEK293-xenografted mice have significantly increased tumor growth, which is associated with a constitutive, Src-dependent increase in the transcription factor hypoxia-inducible factor-1α and secretion of vascular endothelial growth factor (87).