Then, HER2 mRNA expression was subsequently assessed by RNA in situ hybridization (a technique named RNAscope, the feasibility for HER2 test in breast cancer was validated by our previous studies), which is a visualization method combining molecular signals and an almost intact morphological information of tissues and cells containing natural internal control (non-cancerous area), similar to FISH and IHC (8–10). This evidence concerns the gene ERBB2 and breast cancer.