The inositol 5-phosphatase SHIP1 is a nucleo-cytoplasmic shuttling protein and enzymatically active in cell nuclei

► The inositol 5 phosphatase SHIP1 is localized in nuclear puncta of Jurkat cells. ► SHIP1 partially co-localizes with FLASH, a multifunctional nuclear protein. ► Nuclear and cytoplasmic SHIP1 have the same specific enzymatic activity. ► Nuclear import of SHIP1 is mediated by two canonical nuclear localization signals. ► Inactivation of each NLS inhibited nuclear import and reduced the proliferation.