Next, we investigated the anti-tumor activity of HER2-CAR T cells in a firefly luciferase (ffLuc) activity-based cytotoxicity assay (Figure 3) at an E:T ratio of 1:1 using MDA-HER2.ffLuc, JIMT-1.ffLuc, and N87.ffLuc as target cells. The gene discussed is ERBB2; the disease is neoplasm.