PDCD1 and neoplasm: Because of several elegant experiments, among which are the transfer of PD-1highILC2s in B-NSG mice, the deletion of PD-1 and HS3ST1 from ILC2s by CRISPR-Cas9 technology, the generation of Hs3st1flox/floxId2-CreERT2 mice, the targeting of PD-1 with an anti-PD-1 antibody, Wang et al. demonstrated that PD-1+ and HS3ST1+ ILC2s are involved in CRC tumor progression.