Interestingly, detectable amounts of IMQ (16.31 μM), RSQ (4.47 μM), and GDQ (10.13 μM) are taken up by the 4T1-MDR-derived cancer cell line; however, significant competition for P-gp-mediated efflux was not observed with Rh123 for RSQ and GDQ. This evidence concerns the gene PGP and cancer.