PGP and colon carcinoma: For example, P-gp-overexpressing human colon carcinoma (SW620 Ad300) cells pre-treated with chrysosporazine F (2.5 μM) acquired a gain in sensitivity (GS 14) against the anticancer agent doxorubicin, >2-fold that of the positive control verapamil (GS 6.1), making chrysosporazine F one of the more potent P-gp inhibitors reported to date [5].