EPCAM and hepatocellular carcinoma: Indeed, PCDH18 knockdown in EpCAM-positive HCC2 cells resulted in a slightly enhanced rate of proliferation, indicating that the requirement for PCDH18 expression may have been bypassed in EpCAM-positive HCCs; in EpCAM-negative HCC cell lines, PCDH18 knockdown instead inhibited cell proliferation.