TDO2 and glioblastoma: We confirmed that this association holds true at the protein level using immunohistochemistry staining of mesenchymal GBM samples, a GBM subtype in which TDO2 expression is particularly elevated, although in the absence of a tumor cell stain in Figure 2B, we cannot exclude that the CEBP/β staining arises from infiltrating CEBPB-expressing macrophages.