Figure 5. Compound 8.12 synergizes with gefitinib in cell killing in vitro. (A) HepG2, A549, and U87 cells were treated with the indicated range of concentrations of gefitinib in the presence of fixed concentrations of compound 8.12 that are unable to impact on the viability as a single agent. Relative cell viability was plotted against the log of gefitinib concentration, and combination indices (CI) were also plotted against the fraction affected (Fa) value. Details of experimental methods and CI calculation are described in Materials and Methods. ●, DMSO; ■, 0.8 µM compound 8.12; ▲, 1.2 µM compound 8.12. (B) HepG2 cells were treated with either vehicle only, 1.2 µM compound 8.12, 4 µM gefitinib, or both, for 48 h, whereupon cells were harvested and lysates subjected to immunoblot analysis using a LC3 antibody. Data shown are from a single experiment that has been repeated at least twice with similar results.