Contradictorily, the relationship between two histaminergic receptors H1R (promote) and H2R (suppress) in gut inflammation and colonic carcinogenesis was presented in the mouse model, while the ratio of HRH2/HRH1 gene expression was significant in the human colorectal cancer-derived cell lines (HCT116, Caco2, DLD1, LS174T, and HT29) [10]. Here, HRH2 is linked to colorectal cancer.