HIF1A and ischemia: We also demonstrated that mitochondrial ROS induced by ischemia impairs blood flow recovery, and mitochondrial superoxide scavenging improves collateral growth related to downregulation of p53, upregulation of HIF-1α and VEGF in the early phase of ischemia, and preservation of PGC-1α, NRF-1, and ERRα in the late phase of ischemia (Figure 8).