CA9 and glioblastoma: Using the well-established anti-CAIX antibody (α-CAIX) M75 that recognizes the CAIX extracellular domain [11], we could initially confirm that CAIX closely overlaps with the hypoxia marker GLUT1 [12] in patient glioblastoma tumors (Figure 1A), and that CAIX is substantially induced by hypoxia in a patient derived glioma cell-line (U87-MG) in vitro (Figure 1B).