CST's PathScan^® Total SMAD2 Sandwich ELISA Kit #7244 detects endogenous levels of total SMAD2 protein. As shown in Figure 1, both phospho- and nonphospho-SMAD2 proteins from untreated and TGFβ treated MV1LU cell lysates are detected by this kit. In Figure 3, Western blot analysis of protein captured in the SMAD2 Rabbit mAb #3109 coated microwell shows a single band corresponding to the SMAD2 protein. SMAD2 in Hela cells also can be detected by this kit (data not shown). This kit detects proteins from the indicated species, as determined through in-house testing, but may also detect homologous proteins from other species.

Members of the SMAD family of signal transduction molecules are components of a critical intracellular pathway that transmit TGF-β signals from the cell surface into the nucleus. Three distinct classes of SMADs have been defined: the receptor-regulated SMADs (R-SMADs), which include SMAD1, 2, 3, 5, and 9; the common-mediator SMAD (co-SMAD), SMAD4; and the antagonistic or inhibitory SMADs (I-SMADs), SMAD6 and 7 (1-5). Activated type I receptors associate with specific R-SMADs and phosphorylate them on a conserved carboxy-terminal SSXS motif. The phosphorylated R-SMADs dissociate from the receptor and form a heteromeric complex with SMAD4, initiating translocation of the heteromeric SMAD complex to the nucleus. Once in the nucleus, SMADs recruit a variety of DNA binding proteins that function to regulate transcriptional activity (6-8).