SP3 and glioblastoma: Such an alteration in the balance of SUMOylation pathway would not only explain why GBM grown at atmospheric oxygen tensions still display high levels of HIF-1α and why this HIF-1α is located in the nucleus, Figure 4, but why the relationship between the levels of MAOB and Sp3 in the bulk of the GMB is inverted in the astrocytoma and in four of the GBM tumor, Figure 5.