Skp1 also known as p19A, OCP2, Skp1 p19 is a component of SCF complexes, which are composed of this protein, cullin 1, a ring-box protein, and one member of the F-box family of proteins. Skp1 plays a crucial role in the regulation of the cell cycle, particularly in the S phase, where Skp1 associates with cyclin A and cyclin-dependent kinase 2 (Cdk2). This interaction is vital for proper progression of the cell cycle, as cyclin A is essential for the transition from G1 phase to S phase, facilitating DNA replication. Skp1 is part of a larger family of regulatory proteins known as Skp proteins, which are involved in the assembly of cyclin-Cdk complexes. Skp1 p19 presence is necessary for the stability and function of the cyclin A-Cdk2 complex, though Skp1 p19 does not directly regulate the activity of these complexes.