JAK3 inhibitor (IC50 = 1.8 μM) that displays no activity at JAK1 or JAK2. Inhibits STAT1 activation, iNOS expression and NO production in macrophages in vitro. Also inhibits other common kinases including EGFR (IC50 = 4 nM), Src, Abl, VEGFR, MAPK and PI 3-K and induces apoptosis in human glioblastoma cell lines (IC50 = 158 μM).