Tyrphostin AG 490 is a tyrosine kinase inhibitor of JAK2, EGFR, and Neu that belongs to the family of tyrphostins. In acute lymphoblastic leukemia studies the compound has been reported to inhibit JAK2 from B cell precursors. Additionally, Tyrphostin AG 490 has been observed to block cytokine-induced activation of JAK2 in eosinophils and STAT3 activation in T cell lymphoma cells. Unlike other kinase inhibitors, Tyrphostin AG 490 does not inhibit JAK1, Lck, Btk, Tyk2, Syk, Lyn, and Src. Research indicates that Tyrphostin AG 490 inhibits IL-7 mediated proliferation. Inhibition of Jak kinase activity by Tyrphostin AG 490 leads to lower levels of p85 phosphorylation and p-13 kinase activation.