As Figure S1a–d showed, the IC50 of ZA-A, ZA-B and ZA-C were all larger than 40 μM in Flp-InTM-293, ABCB1/Flp-InTM-293 (over-expressing P-gp), HeLaS3 and KB/VIN (multi-drug resistant cancer cells, P-gp overexpression). This evidence concerns the gene ABCB1 and cancer.