ERBB2 and breast carcinoma: A significant difference was found between sHER2 levels of cats with HER2-negative mammary carcinoma (IHC-negative group) and sHER2 levels of cats diagnosed with mammary carcinoma overexpressing HER2 (IHC-positive group), by both ELISA (p = 0.001, Figure 3A) and Dot blot assay (p = 0.03, Figure 3B).