ERBB3 and colon carcinoma: Interestingly, the non-breast derived brain metastases showed similarly high activation of the MAPK pathway together with over-expression (3+ stain) of EGFR (in 9/11 (81%) metastases (a prostate and one colon carcinoma did not) but in the absence of HER3 activation (0/11) (see Additional file 2, Table S1).