Developmental stage: Exclusively expressed in proliferating cells from the transition G1/S until the end of cytokinesis. PTM: Phosphorylated upon DNA damage, probably by ATM or ATR. subcellular location: During mitosis it is strictly associated with the spindle pole and with the mitotic spindle, whereas during S and G2, it is diffusely distributed throughout the nucleus. tissue specificity: Expressed in lung carcinoma cell lines but not in normal lung tissues.