The transcription factor NF-κB is a key regulator of cellular processes. A mechanism that contributes to timely termination of NF-κB activity is UPS-dependent degradation of p65 in the nucleus or on chromatin. The ubiquitin-specific protease that takes part in this process and its molecular mechanisms are shown in previous study, but which structural feature of USP48 was responsible for these effects is unknown. Here, we show that maybe the stability of NF-κB is controlled by proteasome-mediated degradation and ubiquitin-specific protease 48 (USP48), also known as synaptic ubiquitin-specific protease (synUSP) or USP31, can enhance NF-κB stability through proteasome-dependent regulation in the nucleus. USP48 contains a carboxyl-terminal nuclear localizing signal, 938 RHRK 941 , which is responsible for its nuclear translocation. Our results demonstrate a more detailed mechanism for this member of the USP gene family in cellular processes. [ABSTRACT FROM AUTHOR]