The commonly used IHC markers to support a diagnosis of a carcinoma of breast primary include mammaglobin, gross cystic disease fluid protein 15 (GCDFP-15), GATA binding protein 3 (GATA3), and SRY-related HMG box 10 (SOX10), in addition to hormone receptors [1]. The gene discussed is GATA3; the disease is carcinoma.