The levels of CLK3 in CCA and other digestive system cancers are significantly up-regulated and associated with decreased OS. (A) TCGA analysis of CLK3 mRNA expression in 1,508 human digestive system tumors. Data are mean ± SD. **, P < 0.01; unpaired Student’s t test. (B) The survival of patients with high CLK3 expression was poor based on TCGA data in A. **, P < 0.01; Kaplan-Meier analysis. (C) Analysis of CLK3 expression based on open GSE26566 data. Data are mean ± SD. ***; P < 0.001; unpaired Student’s t test. (D)CLK3 mRNA expression in 100 human CCA specimens and matched normal samples was determined by quantitative PCR. (E) CLK3 expression in 100 human CCA specimens was analyzed as follows: level, tumor size, metastasis, and stage. *, P < 0.05; **, P < 0.01; χ-square test. (F) IHC analysis of CLK3 expression in 100 human CCA specimens and matched normal samples. Representative pictures are presented. Bar, 100 µm. **, P < 0.01; χ-square test. (G) Stratified by CLK3 levels in CCA patients (n = 100), Kaplan-Meier analysis of OS is presented. **, P < 0.01. CHOL, cholangiocarcinoma; ESCA, esophageal carcinoma; HCC, hepatocellular carcinoma; HE, hematoxylin and eosin; PAAD, pancreatic adenocarcinoma; READ, rectum adenocarcinoma; STAD, stomach adenocarcinoma; TPM, transcripts per million.