FIGURE 2.

Smad3 is regulated at the level of transcription. A, mRNA levels of Smad2 and Smad3 were detected by RNase protection. Total RNA was isolated from both cycling (C) and quiescent (Q) EpH4 and EpRas cells. 20 μg of total RNA were analyzed by RNase protection with probes for Smad2 and Smad3. The protected fragments (Smad2 or Smad3) are indicated. γ-Actin was used as a loading control. Data are representative of two independent experiments. B, quantitation of RNase protection by phosphorimage analysis. Data are the means and S.D. of two separate experiments relative to appropriate controls.