CREB3L4 and glioblastoma: The PN-L class of tumors was characterized by high levels of activity of TFs showing high influence in the PN and the NL subtypes too, such as SALL2, ZNF704, CAMK4, and CREB3L4, but also by the uniquely high activity of GBX2, the Gastrulation Brain homeobox 2, recently described to act as a tumor suppressor in GBM cells, and inversely correlated to GBM grade39.