We found pronounced cancer cell apoptosis after co-culture with PD-1+ γδ T cells (Vδ1 or Vδ3+) compared with PD-1– cells; cancer cell death was more pronounced in HLA-class-I-negative HCT-15 cells (Fig. 3e and Supplementary Videos 1 and 2). The gene discussed is PDCD1; the disease is cancer.