To determine whether the NSC-secreted anti-HER2 antibody binds specifically to the HER2 receptor, HB1.F3-H2IgG cells were co-cultured overnight with either MCF7 human breast cancer cells that express low levels of HER2, or MCF7/HER2 cells, an MCF7 line stably transfected to overexpress HER2 [16]. Here, ERBB2 is linked to breast carcinoma.