2.10. Immunohistochemical staining

The specimens were selected from patients who had undergone hepatectomy after sorafenib treatment in our institute, and all patients provided written informed consent. This study was approved by the ethics committee of our hospital, and the written informed consent for the use of their resected tissues was obtained from all patients (Approval no. 2900‐2). Sliced specimens were deparaffinized and rehydrated, then blocked with endogenous peroxidase. The samples were incubated with anti‐BAFF (Invitrogen, Thermo Fisher Scientific Inc), anti‐BAFF‐R (#s‐32774, Santa Cruz Biotechnology), and anti‐p65 (Ab16502, Abcam) primary antibodies for 1 h at room temperature. Then the slides were incubated with EnVision Dual Link System‐HRP secondary antibody (Dako), treated with diaminobenzidine (Wako), and Mayer's hematoxylin (Muto Pure Chemicals Co. Ltd.). Lastly the samples were observed under a fluorescence microscope (Keyence Corporation).