ATM-mediated NuSAP phosphorylation induces mitotic arrest

► Ectopic expression of NuSAP lead to mitotic arrest observably dependent on the kinase activity of ATM. ► ATM interacts with NuSAP and phosphorylates NuSAP on Ser124. The phosphorylation and interaction occur specifically at G2/M-phase. ► Our work has uncovered an ATM-dependent checkpoint pathway that prevents mitotic progression by targeting a microtubule-associated protein, NuSAP.