Downregulation of the small GTPase Ras-related nuclear protein accelerates cellular ageing

► Small GTPase Ran decreases in normal mammalian cells in a passage-dependent manner. ► siRNA-mediated depletion of Ran causes cellular senescence in human fibroblasts. ► Ran-depletion causes nuclear accumulation of importin α. ► Nuclear accumulation of importin α occurs in old cells and cells lacking CAS. ► CAS-depleted cells also exhibit cellular senescence.