Immunohistochemistry (IHC) Staining Protocol

IHC staining was performed as described previously [26 (link)]. Briefly, sections that adhered to slides were deparaffinized with xylene and rehydrated with alcohol. After submerging into EDTA antigenic retrieval buffer, diluted hydrogen peroxide (0.3%) was used to inactivate endogenous peroxidase activity, followed by incubation with 5% bovine serum albumin (BSA) and the primary antibody (listed in Supplementary Table 2) overnight at 4°C. Then, the sections were stained with a horseradish peroxidase (HRP)-labelled secondary antibody (Gene Tech, Shanghai, China) and diaminobenzidine (DAB, Gene Tech). Finally, the slide was counterstained with haematoxylin, dehydrated in ethanol, cleared in xylene, and coverslipped. IHC scoring was performed by Image-Pro Plus v6.0 software (Media Cybernetics, Inc., Bethesda, MD).