NCAM1 and neoplasm: In addition, the infiltration and IFN-γ secretion of CD56-expressing CAR-T cells in the tumor tissues were significantly elevated in comparison with that of CD56mut-expressing CAR-T cells (Fig. 4c), which indicated that the homophilic interaction of CD56 was important for the infiltration, survival, and antitumor activity of Her2-CAR-T cells.