A cell-permeable indazolylimidazopyridazinamine compound that acts as a potent and reversible inhibitor of histone kinase haspin activity (IC50 = 2nM) with moderate selectivity over TrkA, GSK-3β, PIM1, Cdk1/B and Cdk2/A (% inhibition at 100nM = 58, 48, 36, 34 and 33, respectively) among a panel of 27-kina