PTPA and glioblastoma: Hofstetter et al., through the study of PP2A expression and activity in GBM, investigated whether PP2A activity in GBM is induced by hypoxia and whether it is involved in regulation of cell cycle progression and survival of severely hypoxic tumor cells; interestingly, PP2A mediates the energy consumption reduction of hypoxic TSCs (tumor stem-like cells), which enhances tumor cell survival [24].