IRS4 and obesity due to melanocortin 4 receptor deficiency: In comparison to control Cre-dependent viral injections into the PVH of IRS4-iCre mice (PVHFlex) or AAV-Flex-TetTox injections in the PVH of wildtype mice (WTTetTox), mice with IRS4PVH neuronal silencing show modest obesity within one week of injection (Fig. 5C: PVHTetTox v.