PGP and neoplasm: The importance of the DpT series of analogues as new anti-cancer therapeutics is demonstrated by (1) their broad and selective anti-tumor activity [7, 8, 26, 27], (2) their ability to inhibit metastasis via up-regulation of NDRG1 or 2 [22–24], and (3) the efficacy of these compounds to overcome Pgp-mediated drug resistance [10, 12, 13].