CD9 and malignant glioma: The involvement of CD9 and IGSF8 in glioma progression is consistent with our findings in PCa: elevation of CD9 expression and downregulation of IGSF8 correlated with progression of malignant glioma [95, 96], Although IGSF8 is frequently downregulated in gliomas, cBioPortal does not show any rearrangements of IGSF8 in gliomas.