Although PD-1 was highly expressed in blood-recovered CAR (B2) T cells (Figure 6G), the CAR (B2) T cells recovered from mouse spleens still efficiently lysed MDA-MB-231 tumor cells (Figure 4G), probably because of B2 VNAR blocking the interaction of PD-1 with PD-L1, although not entirely. Here, PDCD1 is linked to neoplasm.