Fig. 4

Effect of erlotinib, nelfinavir and nitroxoline as single agents or in combinations on AsPC-1, Capan-2 and BxPC-3 cell viability. Cell viability was assessed by MTT assay after incubation for 48 h with nelfinavir, or nitroxoline at low (a, c and e), or high concentrations (b, d and f) as single agents and in combinations with or without a fixed dose of erlotinib. The combination index (CI) for each drug combination was calculated by CompuSyn. To allow CI calculations two concentrations of nelfinavir, nitroxoline and erlotinib were included in each experiment. Cell viabilities at low concentration of erlotinib used for CI calculations are reported in Table S1. CIs resulted synergistic (CI < 1) for some combinations in Capan-2 (c, d) and BxPC-3 (f). Data shown are the means ± SD of three experiments with quintuplicate determinations