KLRD1 and bladder transitional cell carcinoma: Single-cell analysis revealed that KLRD1 is predominantly expressed in NK cells and CD8Tex cells across various cancers, particularly in bladder cancer (BLCA), HNSC, KIRC, non-small cell lung cancer (NSCLC), pancreatic cancer (PAAD), peripheral blood mononuclear cells (PBMC), and SKCM (Figure 2A).