MWCNTs with a dense coating of phospholipid PEG exhibiting minute nonspecific cell interactions but immense intercellular diffusion, chemically modified with an anti-P-glycoprotein (Pgp) antibody showed highly Pgp-specific cellular uptake, were strongly cytotoxic to multidrug-resistant (MDR) cancer cells upon photoirradiation but they were not toxic and phototoxic to cells, which do not express Pgp, suggesting their suitability for successful therapy of MDR cancers [301]. This evidence concerns the gene PGP and cancer.