MMP1 and obesity due to melanocortin 4 receptor deficiency: The aforementioned experiments demonstrated that reduced collagen II in the cartilage of male neonatal mice of obese mothers might be associated with the decreased levels of RUNX2 and SOX9 and also with the elevated expression of MMP1 and reduced expression of TIMP1, further adding to the evidence of cartilage matrix damage in male neonatal mice in the maternal obesity group.