COL23A1 and nonpapillary renal cell carcinoma: Furthermore, immunohistochemistry (IHC) performed in 151 ccRCC tissue samples revealed that COL23A1 protein was mainly localized in cytoplasm with or without cytomembrane staining (Fig. 2A–D), while COL23A1 expression was low in normal kidney tissues (Fig. 2E,F).