HIF1A and glioblastoma: 125 Not only is the TSC1–TSC2 complex maintained in its active form (phosphorylation of TSC1) by AMPK, but it is also activated by the REDD1 (regulated in development and DNA damage responses 1) protein, itself activated under hypoxic condition; then autophagy is induced by preventing TSC2 phosphorylation and sequestration by the 14-3-3 protein.126 An interesting study on GBM cell lines showed that hypoxia induced autophagy.115 This signaling was preceded by a stabilization of HIF1α and an increase in phospho-AMPK (active AMPK).