Figure 6.

Cytotoxicity of doxorubicin (a), etoposide (b) and methotrexate (c) in monolayers or multicellular spheroids from PSC-1 (P-gp^neg) clone cells in comparison to the parental INER-51 cell line. Cytotoxicity was measurement by the MTT colorimetric assay and expressed as percent growth inhibition in comparison with the untreated tumour cells. Each point represents the mean of at least 3 independent experiments and error bars are the standard error of the mean