ERBB2 and breast cancer: Meanwhile, EdU staining further verified the above results (Figures 4C–E), although the anti-HER2 IVIg treatment showed a significant inhibitory effect on two breast cancer cell lines (p = 6.33 × 10−7 for SK-BR-3 cells and p = 1.08 × 10−8 for BT-474 cells), as compared with regular IVIg treatment (Supplementary Figures S1C,D).