The present application provides novel human genes WDRPUH and KRZFPUH, and PPIL1 whose expression is markedly elevated in a great majority of HCCs and colorectal cancers, respectively, compared to corresponding non-cancerous tissues, as well as novel human gene APCDD1 whose expression is elevated in primary colon cancers and down-regulated in response to the transduction of wild-type APC1 into colon-cancer cells. The genes and polypeptides encoded by the genes can be used, for example, in the diagnosis of a cell proliferative disease, and as target molecules for developing drugs against the disease.