Involved in modulation of cell growth and cellular response to gamma radiation probably via regulation of the Akt signaling pathway. Involved in regulation of p53/TP53. Suppresses p53/TP53 protein levels and promotes its ubiquitination; the function is dependent on USP7 and independent on MDM2. Proposed to displace p53/TP53 from interaction with USP7. Interacts with USP7. Belongs to the nucleosome assembly protein (NAP) family. Extended N-terminus.