PIAS1 and glioblastoma: Components of the SUMOylation pathway are also upregulated in both GBM samples and cell lines, including E1 (SAE1), E2 (Ubc9), and E3 (PIAS1 and 3) components as well as a SUMO-specific protease (SENP1) (Figure 1) [64,70,88,89,90].