Fig. 6. Nitric oxide (NO) regulates many of the physiological processes that are characteristic traits of icefish. NO stimulates angiogenesis through the activation of vascular endothelial growth factor (VEGF). Mitochondrial biogenesis is induced by NO via peroxisome proliferator-activated receptor coactivator 1 (PGC-1). NO has also been shown to induce muscle hypertrophy, although this molecular pathway has yet to be defined. The authors acknowledge the use of Scienceslides (Visiscience Corp.) in creating this figure.