GRP78(Glucose regulated protein 78) also known as BiP, HSPA5 is a member of the heat shock protein 70 (HSP70) family, primarily localized in the endoplasmic reticulum (ER) of cells. GRP78′s presence in the ER is vital as a molecular chaperone, ensuring correct folding and assembly of nascent proteins while maintaining protein homeostasis. This function is essential for preventing misfolded protein accumulation, which can lead to ER stress and activate the unfolded protein response (UPR), a critical cellular stress response associated with various diseases, including cancer and neurodegenerative disorders. GRP78 interacts with several specific proteins, including ATF6, IRE1, and PERK, which are key players in the UPR pathway.