TIAR is an ubiquitously expressed RNA-binding protein, which regulates translational control, splicing, and other activities, including apoptosis. TIAR attenuates CDK1 activity, and is essential for the G2/M checkpoint. It accumulates in nuclear foci in late G2 phase and prophase in cells under replication stress. In steady state TIAR shuttles between the cytoplasm and the nucleus, probably as a part of nucleocytoplasmic transport of mRNA, but under stress conditions it accumulates mRNA molecules in granules and prevents their translation. Nucleolytic activity of TIAR against attacked target cells of cytotoxic lymphocytes has also been reported. Similarly, e.g. in permeabilized thymocytes TIAR triggers DNA fragmentation.
