ERBB2 and neoplasm: By delivering costimulatory domains to tumor cells using a tumor-localizing vIgD (such as NKp30 localization to B7H6+ tumor cells; Figure 8) or a tumor specific monoclonal antibody (such as trastuzumab localization to HER2+ tumor cells; Figure 9), T cell responses can be enhanced in the absence of tumor-expressed costimulatory proteins.