Resistance of tumor cells to chemotherapy, such as 5‑fluorouracil (5‑FU), is an obstacle for successful treatment of cancer. As a follow‑up of a previous study we have investigated the effect of conditioned media (CM) from macrophages of M1 or M2 phenotypes on 5‑FU cytotoxicity on the colon cancer cell lines HT‑29 and CACO‑2. HT‑29 cells, but not CACO‑2 cells, having been treated with a combina...