Fig. 2.

The effect of EGFR inhibitors and FTY720 on cell proliferation measured by IncuCyte real-time imaging. Data are expressed as the change in percent confluence, corrected for confluence at time zero, and are mean values ± SD at each time point, generally from triplicate wells for each treatment. Treatments are: control (blue), gefitinib (red, except in panel (d), erlotinib), FTY720 (orange), and both drugs combined (green). Drug concentrations (μM) for each cell line are designated as follows: G1 = gefitinib, 1 μM; E3 = erlotinib, 3 μM; F1 = FTY720, 1 μM; G1F1 = gefitinib, 1 μM + FTY720, 1 μM, etc. CI = combination index, a measure of drug synergy, calculated according to Ref. 25. Mammary carcinoma cell lines are: a HCC1806; b MDA-MB-468; c HCC70; d HCC1806, treated with erlotinib in place of gefitinib; e MDA-MB-231; f BT549; g Hs578T cells stably expressing empty shRNA vector (shCON); h Hs578T cells stably expressing IGFBP-3 shRNA (shBP3). Panel (h) inset: relative IGFBP-3 mRNA levels in Hs578T cells stably expressing shRNA vector or IGFBP-3 shRNA. i superimposed curves for control (no treatment) and G2.5 F1 (combination treatment) in shCON (solid circles) and shBP3 (open circles) Hs578T cell lines. IGFBP-3 insulin-like growth factor binding protein-3