Copyright information:Taken from "Heregulin β1 drives gefitinib-resistant growth and invasion in tamoxifen-resistant MCF-7 breast cancer cells"http://breast-cancer-research.com/content/9/4/R50Breast cancer research : BCR 2007;9(4):R50-R50.Published online 8 Aug 2007PMCID:PMC2206726. Examples of high and low HRGβ1 expression. Scale bars = 20 μm. Box-plots illustrating cytoplasmic HRGβ1 immunohistochemistry assessed by H-score analysis in membrane (mem) epidermal growth factor receptor (EGFR)-negative, erbB2-negative and erbB3-negative primary breast cancer versus membrane EGFR-positive, erbB2-positive and erbB3-positive primary breast cancer. A significant positive correlation between cytoplasmic HRGβ1 expression and membrane erbB receptor positivity was only seen with EGFR (Mann–Whitney U test, = 0.04). Box-plots illustrating cytoplasmic HRGβ1 immunohistochemistry assessed by H-score analysis in membrane (mem) phosphorylated erbB2-negative versus membrane phosphorylated erbB2-positive primary breast cancer and in nuclear (nuc) phosphorylated ERK1/2-negative versus nuclear phosphorylated ERK1/2-positive primary breast cancer (Mann–Whitney U test, = 0.006 and = 0.017, respectively), and scatter plot illustrating the significant positive correlation between expression levels of nuclear phosphorylated AKT and cytoplasmic HRGβ1 in the same samples (Spearman rank test, = 0.044).