Serine/threonine haspin-like protein kinase involved in cell cycle regulation. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Absent in G1-arrested cells and accumulates in G2-M. The KEN and D (destructive) boxes are required for the cell cycle-controlled ALK2 degradation by the anaphase promoting complex (APC) pathway. The protein kinase domain is predicted to be catalytically inactive. However, weak kinase activity was experimentally demonstrated. Periodically phosphorylated during the cell cycle with a phosphorylation peak during mitosis and hyperphosphorylated after DNA damage. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family. Haspin subfamily.