LDN-209929 dihydrochloride is a potent and selective inhibitor of haspin kinase (IC50= 55 nM). LDN-209929 dihydrochloride shows180-fold selectivity verses DYRK2 (IC50= 9.9 μM).

Haspin: Haploid Germ Cell-Specific Nuclear Protein Kinase, is a serine/threonine kinase expressed in a variety of tissues (e.g., testis, bone marrow, thymus, and spleen). Haspin also plays an important role in mitosis, where it phosphorylates histone H3 at Thr-3 (H3T3) in G2/early prophase, becomes maximal during prometaphase/metaphase and then diminishes during anaphase [1]. DYRKs belong to the CMGC family of ePKs and can be further divided into class 1 kinases DYRK1A and 1B, and class 2 kinases DYRK2, 3, and 4. The activity of DYRKs depends upon autophosphorylation of an essential activation loop tyrosine during synthesis [1].