In addition, due to the limited number of normal brain tissues we collected, the expression of MMP9, TMEM92, C1orf226, CD163, LINC00482, AK5, MICU3, and CD200 in R2 tumor tissue data was also analyzed using the R2 online tool to validate our results and is shown in Fig. 6b. This evidence concerns the gene MMP9 and neoplasm.