Remarkably, GFAP a well-known marker for Glioma-associated astrocytes (GAAs), strongly upregulated in our 3D GBM spheroids by 575-fold (bi-culture with GBM cells) and 337-fold (tri-culture), confirming the successful differentiation towards a GAA-like state [13]. The gene discussed is GFAP; the disease is glioblastoma.