TM9SF3 and cancer: Histologically, TM9SF3 overexpression has been reported in scirrhous‐type GC at both the primary and lymph node metastatic sites, suggesting its potential involvement in tumor invasion.[37] In our study, TM9SF3 was expressed in various subtypes of BrMs as membranous and cytoplasmic staining within cancer lesions but was weakly or not expressed in gliomas (Figure 4D; Figure S9, Supporting Information).