The intrinsic toxicity of DMF can be visualized in Figure 9C; the determined half-maximal growth inhibition concentration (GI50) was 52.7 μM, which matches the findings of impaired cell viability at 50 μM as indicated in Figure 9A. In conclusion, DMF forms DMS-SG in vitro, which is a substrate of ABCC1 and competitively inhibits ABCC1-mediated doxorubicin transport, eventually reversing ABCC1-mediated MDR against doxorubicin in ABCC1-expressing H69AR cancer cells. This evidence concerns the gene ABCC1 and cancer.