ARC and malignant colon neoplasm: However, our attempts to modulate ARC expression by mechanisms previously described in other cell lines were not successful in RCC cells; neither topotecan, as a classic chemotherapeutic compound [19], nor the ERK-inhibitor UO126 [35] were able to downregulate ARC expression, although both mechanisms were previously described to inhibit ARC gene expression in myocardial and colon cancer cell lines, respectively.