ABCC1 and neoplasm: For that reason, the cell population with more expression of ABCC1 (associated with the MDR phenotype, and therefore, it is more resistant) is more sensitive to DNR than the parental population, an effect that was named collateral sensitivity and can be ultimately considered the Achilles’ heel of tumor cells overexpressing ABCC1, owing to the increased efflux of both GSH and GSSG in both basal and cytotoxic conditions, making resistant cells more susceptible to pro-oxidant attacks than sensitive cells, which can be used as an antitumor strategy [69].