In HCC, histamine has dual effects: H1R downregulates β‐catenin/COX‐2 signaling to inhibit growth, H2R promotes proliferation, and H3R's role varies by cell line (antitumor in McA‐RH and protumor in SNU‐368) [71, 73, 315]. Here, HRH3 is linked to hepatocellular carcinoma.