ST3GAL5 and nonpapillary renal cell carcinoma: Furthermore, the protein expression levels of ST3GAL5 and the density of CD8+ cells and PD-1+ cells were positively correlated with each other in ccRCC tissues (r > 0.7, p < 0.001; Figure 6C), suggesting the presence and exhaustion of CD8+ T cells in ccRCC samples with high stage.