PDCD1 and neoplasm: We next employed GEPIA2 to determine the correlations between GZMA, GZMB, GZMK and PRF1 and the signatures of exhausted T cells (HAVCR2, TIGIT, LAG3, PDCD1, CXCL13 and LAYN) and resting (FOXP3 and IL2RA) and effector regulatory T cells (Tregs) (FOXP3, CTLA4, CCR8 and TNFRSF9) in a comprehensive selection of tumor types.