Skp2

Skp2 (S-phase kinase-associated protein 2) is an F-box protein that functions as the substrate-recognition component of the SCF (SKP1-CUL1-F-box) E3 ubiquitin ligase complex and regulates proteasome-dependent turnover of key cell-cycle regulators, most notably the cyclin-dependent kinase inhibitor p27^Kip1^^[1][1]. Mechanistically, Skp2 promotes ubiquitination and degradation of phosphorylated p27, thereby facilitating G1/S transition and sustained cellular proliferation^[1][2]. Through its E3 ligase activity, Skp2 has emerged as a central regulator of cell-cycle progression and oncogenic signaling pathways that influence tumor growth, survival, and stem-cell-associated phenotypes^[1][3]. In cancer models, genetic or pharmacological inhibition of Skp2 suppresses tumor cell survival, impairs cancer stem cell maintenance, and reduces tumor progression, supporting its utility as an experimental target for mechanistic and translational studies^[1]. Compared with related F-box proteins, Skp2 is distinguished by its requirement for the accessory protein Cks1 during efficient recognition and ubiquitination of p27, highlighting a unique substrate-recruitment mechanism within the SCF ubiquitin ligase family^[2]. This functional specificity has motivated the development of Skp2-directed inhibitors and chemical probes designed to disrupt Skp2-mediated p27 ubiquitination and degradation^[4][5]. Therefore, Skp2 represents an important molecular node linking ubiquitin-mediated proteolysis, cell-cycle control, and cancer-associated biological processes, making it a valuable target for experimental research and therapeutic investigation^[1][3].