JAK3i is a highly selective JAK3 inhibitor (IC50: 0.43 nM). JAK3i forms a covalent bond with a cysteine in JAK3, but not the closely related kinase domains in JAK1, JAK2, or TYK2. JAK3i abolishes IL-2-driven T-cell proliferation in vivo and has the potential for autoimmune disease research.
References:
[1]. Geoffrey A Smith, et al. Essential biphasic role for JAK3 catalytic activity in IL-2 receptor signaling. Nat Chem Biol. 2016 May;12(5):373-9.