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Figure S2. Near endogenous levels of Skp2 are sufficient to initiate the Skp2 autoinduction loop. MEFs were starved and infected with increasing amounts of Ad-hSkp2, 180 MOI Ad-Lac Z (shown as 0 MOI Ad-hSkp2), or left uninfected and cycling in 10% FCS. (A) Lysates were prepared after the standard 48-h serum starvation, and Skp2 mRNA and 18S rRNA levels were determined by QPCR. Skp2 mRNA levels were normalized to 18S rRNA and plotted relative to the level of Skp2 mRNA in the uninfected cells. Error bars indicate mean 6 SD. (B) Cell lysates collected after the serum starvation were analyzed by Western blotting for Skp2, p27, and Cdk4 (loading control). Gel units indicate relative molecular mass in kilodaltons.