The immunohistochemistry of mouse TCRβ (to define AFP-TCR+ cells) in tumor 7 days after transferring showed enhanced tumor-infiltrating TCR-T cells in mice receiving AFP-TCR-T with IL-21 (Supplementary Fig. 1c), demonstrating that IL-21 increased the amounts of tumor-infiltrating TCR-T cells, which led to the augmented in vivo antitumor function of AFP-TCR-T. Here, AFP is linked to neoplasm.