This approach has been used to quantify the heterodimerization of ErbB receptors HER2 and HER3 in breast cancer patients and may be a biomarker for metastatic relapse, which is independent of HER2 expression, with a clinical trial assessing this currently ongoing (Barber et al, 2013; Weitsman et al, 2016). Here, ERBB2 is linked to breast carcinoma.