Figures 1B and 1C show typical membranous staining patterns in a tissue defined as HER2 3+ by conventional clinical IHC. CB11 AQUA was positive for both BT474 and SKBR3 cell lines, which are known to over-express HER2 (data not shown). In order to minimize run to run variation, nearly consecutive sections of index tissue microarray YTMA147, which includes breast cancer tissue and breast cancer cell lines, were stained in parallel with test samples for all runs. Pearson's R ranged from 0.88 to 0.98 for YTMA147 (Fig. S1). Here, ERBB2 is linked to breast cancer.