After we used si-TFCP2, the expression TFCP2 was decreased by more than 50%; however, TFCP2 could still bind to the promoter of CD55. After we mutated the binding site of TFCP2, TFCP2 hardly binds to the promoter of CD55 to regulate the expression of CD55. We then performed a ChIP assay and found that TFCP2 directly binds to the promoter of CD55 in colon cancer cells. This evidence concerns the gene CD55 and malignant colon neoplasm.