IL21 and neoplasm: To gain a comprehensive understanding of how IL21 and PD-1 blockade together influence the immune network in the tumor, we performed scRNA-seq of tumor-infiltrating CD45+ immune cells sorted from MC38 tumors in mice treated with control IgG mAb, anti-PD-1 mAb, IL21-anti-HSA, and anti-PD-1 mAb/IL21-anti-HSA.