The conjugation of ubiquitin to proteins is an important means to regulate protein activity for many cellular processes by tagging them for degradation. Removal of Ub can rescue proteins from degradation. This is accomplished by the ubiquitin-specific processing protease (UBP) family of enzymes. Ubiquitin specific peptidase 48 (USP48) is a member of the C19 peptidase family involved in the processing of polyubiquitin precursors as well as that of ubiquitinated proteins. USP48 is involved in the activation of NF-kappa B via its interaction with RELA and TRAF2.