PDCD1 and colorectal carcinoma: However, PD-1+Vδ1+ cells were more responsive to TCR stimulation (anti-TCR-Vδ1 or anti-CD3) compared to their PD-1− counterparts, which is consistent with some data in a recent study of human colorectal cancer (CRC)13 (Fig. 4c and Extended Data Fig. 5c,d).