Additional file 1: Supplementary Figure S1. EDI3 is highly expressed in ER-HER2+ cells and is regulated by HER2. A (left panel), HER2 mRNA expression measured using qRT-PCR. Quantification of A (right panel), HER2 and B, ER protein expression from immunoblotting as represented in Figure 1D. C, Immunofluorescence staining, and D, metabolite levels by NMR in a panel of breast cancer cell lines representing the different breast cancer subtypes. E, HER2 and EDI3 mRNA, and F, protein expression in HCC1954 cells upon HER2 silencing. G, EDI3 and HER2 mRNA expression and H, EDI3, pHER2, and HER2 protein expression in SKBR3 cells after silencing EDI3 with siRNA. I, EDI3 and HER2 mRNA expression and J, EDI3, pHER2, and HER2 protein expression in HCC1954 cells after silencing EDI3 with siRNA. K, Representative Western blots showing EDI3, pHER2 and HER2 protein expression in HCC1954 cells treated with 0.1 µM or 1.0 µM lapatinib for 24, 48, 72 and 96h, with corresponding quantification of protein levels. Data are mean ± SD or mean ± SE for HER2 protein expression in panel A of at least three independent experiments (*, P