To further explore global SUMOylation in the context of the standard GBM chemotherapeutic regimen we examined the levels of SUMO-1 and SUMO-2/3 conjugation after exposure to the alkylating agent temozolomide (TMZ) at concentrations of 50 μM and 500 μM; TMZ did not decrease levels of SUMOylation at these doses. The gene discussed is SUMO1; the disease is glioblastoma.