COL1A1 and neoplasm: To validate the colocalization of STEAP4 and TFE3 in PCa patients, we applied in situ multi‐color immunofluorescence staining using antibodies against COL1A1, STEAP4, and TFE3, and observed STEAP4 and TFE3 double‐positive fibroblasts among the stromal cells within the tumor (Figure 3G).