RTN4 and astrocytoma (excluding glioblastoma): Kuhlman et al. found strong expression of Nogo-A in 71% of oligodendroglioma, but not in other brain tumors, such as: ependymomas WHO grade II, astrocytoma WHO grade I or II, dysembryoplastic neuroepithelial tumors, clear cell meningiomas, as well as metastases to the brain [4].