FIGURE 1.

Half‐maximal inhibitory concentrations (IC50) for etoposide and SN‐38, and protein expression in small cell lung cancer (SCLC) cell lines. IC50 values for etoposide (a) and SN‐38 (b) in SCLC cells were determined by tetrazolium (MTS) assay to identify sensitive and resistant cells. There were no significant differences between sensitive and resistant cells (p = 0.46, 0.35, respectively). (c) Protein expression levels in SCLC cells were evaluated by western blot analysis. GAPDH, glyceraldehyde 3‐phosphate dehydrogenase; TOP, topoisomerase