Sestrins,including sestrin-1 (PA26),sestrin-2 (Hi95),and sestrin-3,are 48 to 65 kDa cystein sulfinyl reductases and they modulate peroxide signaling and antioxidant defense. These proteins selectively reduce or repair hyperoxidized forms of typical 2-Cys peroxiredoxins within eukaryotes. Expression of these proteins is regulated by p53,a tumor suppressor protein. Sestrin 2 is implicated in the regulation of cell growth and survival,in cellular responses to different stress conditions,and also acts as a positive regulator of autophagy. Sestrin 2 is approximately a 57.6kDa protein (480 amino acids).