ERBB2 and breast cancer: Similarly, Melanie Spears et al. employed Proximity Ligation Assays (PLAs) to evaluate the presence of HER2-HER2 and HER2-HER3 dimers in BC tissues and demonstrated that both HER2 gene-amplified and non-amplified BC tissues exhibited detectable levels of HER2 dimers, and the elevated levels of HER2 dimers are associated with larger tumor sizes [38].