AHR induction in response to Trp limitation is mediated through potentially cell type-specific mechanisms involving nuclear factor erythroid 2-related factor 2 (NRF2) signaling in HEK 293 cells and epidermal growth factor receptor (EGFR)-rat sarcoma (RAS)-signaling to the mammalian target of rapamycin complex 1 (MTORC1) and p38/mitogen activated protein kinase (MAPK) in glioblastoma cells [64], [72]. This evidence concerns the gene NFE2L2 and glioblastoma.