SERPINE1 and glioblastoma: In addition, Cluster 3 genes up regulated show enrichment for interactions with the extracellular matrix, integrin signaling, and cell migration (Supplementary Data 2-3), which includes genes that participate in the proneural-to-mesenchymal transition in GBM tumors (e.g., CD44, CDH2/N-Cadherin, SERPINE1, SPP1/Osteopontin)49 (However, this was not observed in vivo—see below).