ABCB1 and cancer: Hence, we prepared CS nanoparticles (NPs) conjugated with the monoclonal antibody against MDR1 (mAb MDR1), which is capable of entrapping the anticancer drug, gefitinib, and chloroquine (CQ)—a known inhibitor of autophagolysosome formation—to explore whether EGFR-TKI resistance could be reversed in EGFR-TKI-resistant cancer cells.