Sulindac sulfide, an active metabolite of the nonsteroidal anti-inflammatory drug (NSAID) sulindac, directly binds to the Ras gene product p21ras in a non-covalent manner. Sulindac sulfide strongly inhibits Ras-induced malignant transformation and Ras/Raf dependent transactivation, due to its action at the most critical site in Ras signaling. Sulindac sulfide was proposed as a lead compound in the search for novel anti-cancer drugs, which directly inhibit Ras-mediated cell proliferation and malignant transformation. Experiments on rodents have revealed that sulindac sulfide effectively inhibited tumor growth in colorectal cancer cell xenografts mice. In addition, was shown, that sulindac sulfide inhibited ABCC1-mediated transport of appropriate endogenous and xenobiotic substrates. The drug was selectivity for ABCC1 as compared with ABCB1 and ABCG2. These properties allow designing novel ABCC1 inhibitors by chemically modifying sulindac sulfide to improve potency and selectivity to inhibit ABCC1-mediated efflux for preventing drug resistance and tumor recurrence or secondary tumor formation following chemotherapy.