Fig. 4: Recombinant IFNs are sufficient to stimulate chemoresistance in MDA-MB-231 and MDA-MB-157 cells.

a MDA-MB-231-GFP/luc cells were cultured with a range of doses of IFNα or IFNγ for 24 h. Cells were then treated with 10 nM epirubicin, or control, and redosed with IFNs. Clongenic survival was determined as previously. b MDA-MB-231-GFP/luc, MDA-468-GFP or MDA-MB-157 cells were cultured with IFNα or IFNγ (2500 pg/ml and 1500 pg/ml, respectively) separately or combination or with appropriate isotype control antibodies for 24 h. Cells were then treated with epirubicin for 24 h (10 nM or, for MDA-MB-157s, 25 nM). Clongenic survival was determined as previously. a, b Data are shown as either colony counts (left), or survival relative to untreated (right) and represent means (±SE) of either 3 (a) or 2 (b) independent experiments. ANOVA tests were performed and selected differences are shown (ns not significant).