ERG and obesity due to melanocortin 4 receptor deficiency: We also analyzed the effects of obesity on blood vessel density in the lung using EC marker, ETS-related gene (ERG) staining; ERG-positive EC density was 2.2- or 2.1- times higher in the C57BL6 or Lepob/+ mouse lungs after PNX compared to those in the sham-operated control mouse lungs, while these effects were suppressed in Lepob/ob mice after PNX (Figures 1B,C).