FGF21 and Hyperglycemia: Protein kinase RNA‐like endoplasmic reticulum kinase (PERK)–eukaryotic initiation factor 2 (eIf2α) branch also activates SREBP1c, and additionally promotes activating transcription factor 4 (ATF4), which in turn stimulates hepatic lipogenesis.[34] Fibroblast growth factor 21 (Fgf21) expression is also upregulated upon ER stress via PERK‐eiF2α‐ATF4 branch of UPR.[33] Fgf21 counteracts ER stress; and by inhibiting lipogenic program, it stimulates glucose uptake in the cells and alleviates hyperglycemia.