Anti-Smad3 (phospho-S423/S425) Antibody

This recombinant rabbit monoclonal antibody from Antibodies.com is raised against Smad3 phosphorylated at the canonical activating residues S423 and S425, the sites directly modified by the TGF-β type I receptor (ALK5) within the C-terminal SSVS motif of the MH2 domain. Detection of these phosphorylated residues is widely used as a readout of canonical TGF-β pathway activation and downstream transcriptional responses involving Smad3/Smad4 complex formation and nuclear translocation.

Validated for Western blot, immunocytochemistry/immunofluorescence, and immunohistochemistry on human and mouse samples, the antibody is supplied as a 50 µl aliquot in TBS (pH 7.4) with 1% BSA, 40% glycerol, and 0.05% sodium azide as preservative. The unconjugated format allows flexible pairing with secondary reagents of the researcher's choice, and a typical workflow involves stimulation of cells or tissues with TGF-β1 (or related ligands) before lysis in the presence of phosphatase inhibitors to preserve the S423/S425 phosphorylation mark.

Common research applications include studies of TGF-β signaling in fibrosis models, epithelial-mesenchymal transition assays, cancer cell invasion work, and immune cell differentiation experiments, where endogenous Smad3 activation can be tracked alongside total Smad3 levels for normalization across blots.