Metformin was discovered to upregulate heat shock protein family A member 5 (HSPA5, Bip), DNA damage-inducible transcript 3 (DDIT3, CHOP), and caspase-12 and induce endoplasmic reticulum stress and endoplasmic reticulum stress-associated apoptosis in vitro and in vivo in thyroid cancer [117]. Here, DDIT3 is linked to thyroid cancer.