Furthermore, we carried out IHC staining for Gab1 and IF co-staining for Gab1 and EpCAM to further determine Gab1 expression in these clinical tumor samples from three major subtypes of BCa, i.e. luminal BCa (n = 6 for IHC and n = 6 for IF), HER2 BCa (n = 6 for IHC and n = 6 for IF) and triple negative breast cancer (TNBC, n = 6 for IHC and n = 6 for IF), respectively (Additional file 2: Figure S1b, S1c and Additional file 3: Table S2, Table S3). Here, ERBB2 is linked to triple-negative breast carcinoma.