Figure 8.

Long-term IGF1 treatment induces resistance to conventional chemotherapeutic agents. Percentage of viable VH-64 cells incubated for 72 hours in the absence (□) and presence (■) of IGF1 (100 ng/mL), followed by incubation for 18 hours with the indicated concentrations of (a) DOX and (b) VP16. (c) Percentage of viable VH-64 cells incubated for 30 min in the absence and presence of 20 μM z-DEVD-fmk and 20 μM z-VAD-fmk, followed by incubation for 18 hours with DOX (1.5 μM), VP16 (20 μM), and serum-free medium alone (Control). Error bars: mean ± SD of triplicate determinations from 4 independent experiments.