VCP and inclusion body myopathy with Paget disease of bone and frontotemporal dementia: Consistent with the hypothesis that VCP disease phenotypes are due to increased activity on substrates, we find that VCP ATPase activity inhibitors such as NMS-873 and ML240 can significantly rescue mitochondrial defects, disrupted muscle integrity and muscle cell death in vivo in Drosophila, and mitochondrial fusion and respiration defects in IBMPFD patient fibroblasts.