DSG2 affects PI3K signaling in vascular endothelial cells, and MMP-9 is involved in DSG2-mediated vascular changes in Moyamoya disease to balance pro-angiogenic and anti-angiogenic factors, thus resulting in abnormalities in endothelial cell proliferation, migration, tube formation, and apoptosis, which are associated with Moyamoya disease vascular remodeling (Fig. 7). This evidence concerns the gene MMP9 and Moyamoya disease.