Consistent with the above findings, the IHC staining assay revealed that the protein level of HDAC8 in the ccRCC tissue microarray was positively correlated with the protein level of CD31, which is a marker of blood vessels (n = 38, Spearman correlation r = 0.4211, P = 0.0085) (Figure 2D). This evidence concerns the gene PECAM1 and nonpapillary renal cell carcinoma.