ERBB2 and breast carcinoma: Using the PLA technique (primary plus secondary antibodies conjugated to oligonucleotides), high levels of HER2-HER2 and HER2-HER3 protein proximity have previously been shown to be correlated with HER2 amplification/overexpression, using 88 and 74 cases of human breast carcinomas for HER2-HER2 and HER2-HER3 PLAs, respectively [24].