We also treated two different HCC cell lines depleted of CD13 with the proteasomal inhibitor MG132 and found that decreased HDAC5 protein levels in these cells were ameliorated by MG132, strengthening that CD13 regulates HDAC5 protein stability via preventing HDAC5 ubiquitination (Figure 6B). This evidence concerns the gene ANPEP and hepatocellular carcinoma.