ABCB1 and cancer: Analysis of anti-proliferative effect on the panel of cancer cell lines indicates that 3-nitropyridine compounds are not substrates for the multidrug resistance efflux pumps, as P glycoprotein or MRP, since the compounds are still efficient on HCT-15 [18–20], NCI/ADR-res [19, 20], UO-31 [19–21] and CAKI-1 [19, 22].