ERBB2 and breast cancer: This was further confirmed with flow cytometry analysis on the two selected cell types that are representative of different breast cancer cell subtypes and that express a range of NLGN4X; MCF-7 (ER+/PR+/HER2−/low NLGN4X) and MDAMB231 (ER−/PR−/HER-/very high NLGN4X).