Potent, selective inhibitor of Janus tyrosine kinase 3 (Jak3)
which binds competitively to the Jak3 ATP site. pIC50 values are
6.8, 5.0, 4.7, and < 5.0 for Jak3, EGFR, Jak1 and CDK4respectively. Inhibits STAT-5
phosphorylation and T-cell proliferation.