Furthermore, IHC staining of 54 cases of cholangiocarcinoma tissue suggested that the expression of Ki-67 was markedly downregulated in USP9X high samples (Fig. 2L, M) but upregulated in USP9X low samples, which demonstrated that the expression level of USP9X was negatively correlated with Ki67 expression. This evidence concerns the gene USP9X and cholangiocarcinoma.