Expression of the feline orthologue of the HER2 gene, f-HER2 (whose kinase domain is 92% similar to the HER2 kinase domain), has been found to be increased in feline mammary carcinoma (FMC) cell lines and tissue samples, and the anti-human HER2 antibody strongly stained 13/36 (36%) FMC archival tissues samples (FMC is a highly aggressive, mainly hormone receptor–negative cancer, that been proposed as a model for poor prognosis triple negative breast cancer in humans) [103]. The gene discussed is ERBB2; the disease is triple-negative breast carcinoma.