SIRT3 and neoplasm: In addition, HIF-1α protein levels and the expression of HIF-1α target genes were analyzed, and the expression of Vefg-a and Pdk1 were significantly increased in SIRT3-deficient tumor tissues, compared with the controls, as was the degree of angiogenic activity, as determined by immunostaining for the endothelial cell-specific marker CD31 (Figure 1G-1I).