ATF4 and cancer: Stress releases BiP from the ER sensor and induces the phosphorylation and dimerization of IRE1 and PERK in cancers, whereby active PERK promotes the phosphorylation of eukaryotic initiation factor 2α (eIF2α) and inhibits protein translation by the activation of activating transcription factor 4 (ATF4) [123,124], and X-box binding protein 1 (XBP1) expression is achieved through ATF6 activation [125].