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Figure S2. Purified recombinant GST-Imp, Smad1, and Smad3 proteins. Full-length human Imp8, Smad1, and Smad3 were expressed in Escherichia coli as GST-fusions and purified on glutathione-conjugated Sepharose beads. The GST moiety was cleaved from Smad1 and Smad3. The final products were resolved by SDS-PAGE and stained with Coomassie blue. Asterisks mark the full-length GST-Imp8, Smad1, and Smad3. Arrows indicate two fragments of Smad1.