As a PCK, PCK2 catalyzes the GTP-driven conversion of OAA to PEP as a rate-limiting step in gluconeogenesis. This conversion step serves as a bridge between glycolytic and TCA cycle intermediates in the mitochondria. In pancreatic β-cells, PCK2 regulates glucose-stimulated insulin secretion by recycling GTP generated from the succinyl-CoA synthase reaction. This drives the TCA cycle, converting PEP to pyruvate to acetyl-CoA for the citrate synthase reaction.[9] Since nearly all of the glycolytic reactions upstream of PEP and downstream of glucose-6-phosphate (G6P) are reversible, PCK2-mediated synthesis of PEP could fuel multiple biosynthetic processes, such as serine synthesis, glycerol synthesis, and nucleotide synthesis. Notably, PCK2 preferentially converts OAA derived from lactate and, thus, can promote biosynthesis even under low-glucose conditions. As a result, PCK2 activity contributes to cell growth and survival during stress. While PCK1 is mainly expressed in the liver and kidney, PCK2 is ubiquitously expressed in various cell types, including leukocytes and neurons, as well as in non-gluconeogenic tissues, including pancreas, brain, heart. Moreover, while PCK1 expression is regulated by hormones or nutrients involved in gluconeogenesis, PCK2 is constitutively expressed. These differences indicate that PCK2 may also perform non-gluconeogenic functions.