ABCB1 is one of these genes that encodes P-glycoprotein (P-gp), an ATP-binding cassette (ABC) efflux transporter involved in multidrug resistance (MDR) in breast cancer, which expels chemotherapeutic drugs from cells, reduces drug efficacy, and contributes to treatment failure (Miao et al., 2017). The gene discussed is PGP; the disease is breast carcinoma.