Haspin (EC 2.7.11.1)is a serine/threonine kinase that phosphorylates Thr-3 of histone H3 in mitosis. This phosphorylation generates a binding site on H3 for Survivin and thereby positions the Chromosome Passenger Complex at centromeres to regulate chromosome segregation, and it also displaces proteins such as TFIID that normally bind to H3 through methylated Lys-4. Depletion of haspin by RNA interference, or microinjection of H3T3ph antibodies, causes chromosome alignment defects and failure of normal mitosis. Haspin kinase inhibitors are expected to be useful probes for elucidating the cellular roles of this protein and may have therapeutic utility in treating cancer[1].