DDIT3 and glioblastoma: Perifosine and also the ether lipid edelfosine can induce autophagy by evoking an ER stress response, as demonstrated by a two- to threefold increased expression of the apoptotic transcription factor CHOP (C/EBP homologous protein)/GADD153 (growth arrest and DNA damage inducible gene 153) in human hepatoblastoma HepG2 cells, but not in human glioblastoma U-87 MG cells.