ERBB2 and breast carcinoma: Based upon the expression of hormone receptors, the subtypes of breast carcinoma are as follows: either estrogen (ER) or progesterone (PR) receptor positive (ER/PR+/−), neither ER nor PR positive (ER/PR−/−), HER2 positive (HER2+) (they show overexpression of oncogene ERBB2) and devoid of any receptors called triple negative (TNBC).