According to the analysis of downloaded TCGA-CHOL RNA sequencing data, there was relevance between the expression of ARHGAP21 and the histological type of CCA (p < 0.05; Figure 2E), and the high expression of ARHGAP21 occurred in the perineural invasion group (p < 0.05; Figure 2F). This evidence concerns the gene ARHGAP21 and cholangiocarcinoma.