... within the upstream promoter. Upregulation of Skp1 is followed by a 2–3-fold increase at the proteinlevel, and could explain in part the role of DLf in blocking cell cycle progression.Skp1 is involved ... as cyclins and cyclin-dependent kinase inhibitors, and at the G1⁄ S transitionit is involved in the recruitment of cyclin E, cyclin A,p21 and p27, leading to their degradation by the pro-teasome ... and that the reactions remainedwithin the exponential phase of amplification. Thus, the rel-ative intensity of the various PCR signals reflects the initialabundance of the corresponding transcripts....