PTPN9 and cholangiocarcinoma: To further clarify the potential resistance mechanism, we analyzed the PTPN9 expression in tissue sections from CCA patients who exhibited non-response or response to surufatinib treatment (Fig. 1A, B), and found that PTPN9 expression was significantly lower in surufatinib-non-response CCA tumor tissues, indicating a potential role of PTPN9 in surufatinib resistance in CCA (Fig. 1C, D).