HRH4 and malignant colon neoplasm: Nevertheless, the receptor has been reported in two well-known human colon cancer cell lines, HT29 and HCT116, and the mammary carcinoma MDA-MB-231 [24], [25], prompting us to verify whether the H4R agonist CB inhibited their proliferation, which was not the case since at optimal concentrations (10−5 M) neither the growth of these cells (Fig. 7A) nor their sensitivity to the anti-neoplastic drug 5-FU were affected, as illustrated for the HCT 116 cell line in Fig. 7B.