May be involved in the response of cells to X-ray radiation. Expressed predominantly in testis followed by prostate and ovary. Low levels found in other tissues including peripheral blood leukocytes, spleen, thymus, small intestine and colon. Also expressed in neuroblastoma, glioma, breast, lung, leukemia, renal, ovarian, prostate and colorectal cancer cell lines. By X-ray irradiation immediately after exposure and is then down-regulated two-fold in an X-ray radiation-resistant cell clone. Responds differently to X-ray radiation in clones of varying radiation responses. Gene model based on mouse cDNA data.