PDCD1 and neoplasm: Among the eight clusters of tumor-infiltrating FOXP3-CD4+ T cells, the signatures of the tumor-infiltrating CD4+_MKI67 cells identified by us (Fig. 8G), the CXCL13+ Tht cells identified by Cohen et al. [39] (Fig. 8H) and the tumor-infiltrating CD4+ T cells in CE9 identified by Luca et al. [19] (Fig. 8I) were highly enriched in the CD4+_CXCL13 (cluster 4) population and, to a lesser extent, in the CD4+_PDCD1 (cluster 3) population (Fig. 8G–I, Supplementary Fig. 12B).