ADRA2C and cholangiocarcinoma: As illustrated in Figure 1A, compared with normal group, ADRA2C mRNA expression level was higher in cholangiocarcinoma (CHOL), colon adenocarcinoma (COAD), head and neck squamous cell carcinoma (HNSC), liver hepatocellular carcinoma (LIHC), rectum adenocarcinoma (READ) and thyroid carcinoma (THCA).