TCPTP-deficiency in POMC-TC mice increased c-Fos staining (a surrogate marker of neuronal activation) in the PVH of fasted mice and this was exacerbated by insulin (Figure 1m); although systemic insulin administration resulted in hypoglycemia, this was similar in Ptpn2fl/fl and POMC-TC mice (Figure 1—figure supplement 2). This evidence concerns the gene PTPN2 and Hypoglycemia.