SKP2 enzyme is a substrate recognition component of the SCF E3 ubiquitin ligase complex which is involved in the ubiquitination and subsequent proteasomal degradation of target proteins which take part in cell cycle progression， signal transduction and transcription. SKP2 specifically recognizes phosphorylated CDKN1B/p27kip and is involved in regulation of G1/S transition. SKP2 gene is recognized as a protooncogene regularly involved in the pathogenesis of lymphomas. SKP2 is part of the F-box protein family which is known for its 40 amino acid motif， the F-box. F-box proteins comprise 1 of the 4 subunits of ubiquitin protein ligase complex called SCFs， which play a role in phosphorylation-dependent ubiquitination. There are 3 F-box classes: Fbws having WD-40 domains， Fbls having leucine-rich replicates， and Fbxs having either diverse protein-protein interaction or no recognizable motifs. SKP2 is part of the Fbls class.
