GFAP and central nervous system cancer: These cells most commonly resembled glia, expressing markers of astrocytes like GFAP, AQP4, and ALDOC and oligodendrocyte progenitors like OLIG1, OLIG2, and PDGFRA. Because transformed glioma cells typically resemble glia at the level of gene expression, we considered these cells to be putatively transformed [6] and attempted to validate these candidate transformed cells by orthogonal means.