Most importantly, it is believed that obtaining correct answers to these questions can help control the activities of P-gp in clinical settings for more effective delivery of drugs into cancer cells by: (1) rational development of novel, targeted therapeutics that bypass P-gp’s action; (2) screening for drugs that reverse the action of P-gp; and (3) looking for compounds that induce cytotoxicity in the presence of P-gp. Here, PGP is linked to cancer.