To analyse the role of sialic acid in PMN mediated ADCC, neuraminidase or STi treated breast tumor cells were subjected to chromium release assays with the EGFR antibodies cetuximab (human IgG1) or panitumumab (human IgG2) for MDA-MB-468, and with the HER2 antibody trastuzumab as human IgG1 or IgG2 for SK-BR-3 - comparing the results to untreated cells. Here, ERBB2 is linked to breast neoplasm.