MAP4K4 and hyperinsulinism: To determine whether Map4k4 was indeed expressed in pancreatic islets in vivo and could potentiate hyperinsulinemia, islets were isolated from Flox/Flox animals fed chow or HFD, mRNA was extracted, and Map4k4 mRNA levels were assessed and normalized to 36b4. A 3-fold increase in Map4k4 mRNA expression was noted in Flox/Flox animals fed HFD for 16 weeks compared with chow diet (Fig. 2F), suggesting that Map4k4 may contribute to HFD-induced hyperinsulinemia in an islet-specific manner.