SF1 and obesity due to melanocortin 4 receptor deficiency: Interestingly, selective elimination of LEPRb in the steroid factor 1 (SF1)-expressing neurons of the VMH also produced an obesity phenotype, with a cumulative effect in mice lacking LEPRb in both SF1 and POMC neurons, indicating that these may represent distinct parallel pathways (Dhillon et al., 2006; Kim et al., 2011b).