Fig. 5From: Characterization of DNA topoisomerase I in three SN-38 resistant human colon cancer cell lines reveals a new pair of resistance-associated mutationsDrug sensitivity assays for parental and SN-38-resistant cells against two non-camptothecin Top1-targeting drugs (NSC 725776/LMP776 and NSC 743400/LMP400) in clinical trial and two clinical Top2-targeting drugs (epirubicin and etoposide). Green solid lines are the parental cells and blue dotted lines are the SN-38 resistant cells. Cells were exposed to drug for 48Â h and cell viability determined using the MTT assay. Shown are representative resultsBack to article page