MMP9 and central nervous system cancer: CD44 is a ubiquitously expressed transmembrane glycoprotein that is involved in cell activation, cell‐to‐cell adhesion and cell‐substrate interaction.[63] CD44 is cleaved by both ADAM 10 and 17 proteases and MMP‐9 in a process that promotes motility via cytoskeletal reorganization.[64, 65, 66] The proteolytically released CD44 extracellular domain (CD44‐ECD) promotes glioma migration and invasion,[65] while the intracellular domain (CD44‐ICD) translocates to the cell nucleus, where it acts as a transcription factor.