ERBB2 and breast carcinoma: For diagnostics purposes, antibodies associated with breast carcinoma include estrogen receptor (ER), progesterone receptor (PR), gross cystic fluid protein (GCDFP), HER-2/neu, cytokeratins (CK5/6, CK7, CK20), and the mucin glycoprotein antibodies, namely, MUC2, MUC3, MUC5AC, MUC6, and DAS-1.