Consistently, MDA-MB-231 cells with MIIP overexpression grew slower and formed smaller tumor masses than the empty vector-transfected control cells in nude mice (Fig. 2E), and tumor tissues formed from MIIP-overexpressing cells had a lower expression of Ki67 and PCNA (Fig. 2F); whereas knockdown of MIIP accelerated in vivo growth of BT549 cells (Fig. S2B). Here, PCNA is linked to neoplasm.