Figure 4. V158411 potentiates gemcitabine, camptothecin, cisplatin and SN38 cytotoxicity in vitro.

A. Curves representing the antiproliferative effect of gemcitabine or camptothecin in HT29 cells in combination with 0 or 400 nM V158411. B. In vitro potentiation of gemcitabine, camptothecin, cisplatin or SN38 cytotoxicity by 400 nM V158411 in p53 proficient or deficient cell lines. Potentiation factor was calculated by IC_{50(cytotoxic agent alone)} / IC_{50(combination treatment)}. C. Colony formation assays in HT29 cells following treatment with gemcitabine, camptothecin or SN38 alone for 24 hours, in combination with 300 nM V158411 for 24 hours or for 24 hours followed by 300 nM V158411 for a further 24 hours. Media was then replaced with drug free and colonies stained after 14 days. Values are the average of 3 independent determinations ± SD.