Figure 4

Dose–response curves to cytotoxic agents of lung cancer cell lines grown as monolayer or spheroids. Cell lines INER-37 or INER-51 as monolayer (●) or MTS (○) were exposed to varying concentrations of etoposide, teniposide, doxorubicin or camptothecin, for 72 h. Drug cytotoxicity was determined by incubation with the tetrazolium dye MTT and measurement of absorbance at 540 nm. Each point value is the average of six independent experiments.