PGP and malignant colon neoplasm: To determine whether the expression of HIF-1α and MDR1/P-gp in colon cancer patients differs, as well as the related sensitivity to chemotherapy, immunohistochemical techniques were employed to detect the expression of HIF-1α and P-gp in the tumor tissues of 120 patients with advanced colon carcinoma who received 5-FU-based chemotherapy.