A DYRK1A inhibitor (Ki = 180 nM; IC50 = 240 nM); selective for DYRK1A over MAOA and B (100 μM); inhibits DYRK1A phosphorylation of tau in COS-7 cells expressing EGFP-DYRK1A and EGFP-tau in a concentration-dependent manner; induces proliferation of human and rat β-cells and increases insulin secretion by human islets in vitro; reverses developmental deformities induced by DYRK1A overexpression in X. laevis embryos,