The findings of this study not only provide a new understanding of the functional regulation of RNF213 and Cav-1 and their effects on NO release in endothelial cells, but also give insights into how disruption of these processes by MMD-related mutations, such as R4810K, can lead to abnormal signaling events that contribute to endothelial cell dysfunction, altered vascular remodeling, and MMD pathogenesis. The gene discussed is CAV1; the disease is multiminicore myopathy.