Differentiation of HER2 gene status in HER2 protein equivocal (IHC 2+) or negative (IHC 0) breast cancer tissues using the HER2 gene-protein assay. The HER2 gene-protein assay carried out on FFPE breast cancer tissue microarray slides was able to differentiate HER2 IHC 2+ cases that were HER2 & CEN17 BISH positive (A) and negative (B). It also distinguished HER2 IHC 0 cases that were HER2 & CEN17 BISH positive (C) and negative (D). [All images 100×.].