ERBB2 and cancer: Supplementing of IFN-γ in cancer cell cultures can downregulate HER2 and blocking IFN-γ in the co-culture system could rescue the HER2 downregulation induced by PBMC and trastuzumab (Figure 4) and IFN-γ played a critical role in the anticancer efficacy of an anti-HER2 mAb therapy [32].