GGCX and obesity due to melanocortin 4 receptor deficiency: By specifically knocking out the key enzymes involved in OCN carboxylation-γ-glutamyl carboxylase (GGCX) and vitamin K epoxide reductase complex subunit 1 (Vkorc1) in bone, they demonstrated that bone-specific knockout of either enzyme significantly reduced OCN deposition in the bone matrix and protected mice from diet-induced obesity and glucose intolerance.