PVR and obesity due to melanocortin 4 receptor deficiency: Impairing PvR signaling in the adult oenocytes, by over-expressing a dominant negative form of the receptor, pvrDN, (oenots>pvrDN) (Brückner et al., 2004) led to obesity phenotypes similar to musts>Pvf1-i flies (Figure 2F, G).