Western blot using affinity purified anti-Smad3 antibody shows detection of endogenous Smad3 in both unstimulated and stimulated cell lysates. Lysates were prepared from control cells (- lanes), or cells stimulated with 2 ng/ml TGF-β lanes for 1 hour. This reagent recognizes both non-phosphorylated and phosphorylated Smad3 protein. Personal Communication. Ying Zhang, NIH, CCR, Bethesda, MD.