Based on limited published evidence, PANO1 (proapoptotic nucleolar protein 1) is a nucleolar protein that functions as an apoptosis inducer and potential tumor suppressor. PANO1 enhances stability of the tumor suppressor CDKN2A/p14ARF by protecting it from proteasomal degradation, thereby increasing p14ARF protein levels 1. Overexpression of PANO1 induces apoptosis under low serum conditions in a p14ARF-dependent manner and suppresses tumorigenicity in vivo 1. PANO1 knockdown reduces p14ARF levels, indicating a regulatory relationship between these proteins.