May be an anti-apoptotic protein involved in DNA repair or cell survival. Accumulates in the nucleus in response to stress. Highly expressed in the testis, spleen and heart. Expressed at high levels in the primary spermatocytes and to a lesser extent in the round spermatids. Also found in the bone marrow, brain, lung, kidney and liver. Strongly induced by a wide range of stress signals: nitric-oxide, gamma- and UV irradiation, hydrogen peroxide, adriamycin and cytokines and this induction is dependent on p53/TP53. Expression is low in resting cells and increases almost 50-fold as the cells progress through the S phase.