TTT-28 is a synthesized thiazole-valine peptidomimetic, a novel selective inhibitor of ABCB1 (P-gp/MDR1) with high efficacy and low toxicity, which reverses the ATP-binding cassette sub-family B member 1 ( ABCB1 )-mediated multidrug resistance (MDR) by selectively blocking the efflux function of ABCB1.