Figure 6.

SMAD3 but not SMAD4 may participate in SBS/protein complex formation. (A) Nuclear extracts were prepared from dermal fibroblasts (DF) treated (+) or not (−) with TGF-β for 30 min or from Flag-SMAD3 transfected cells. Their ability to bind the COL7A1 SBS was compared by EMSA. Note the identical migratory pattern of the TGF-β-specific band with the Flag-SMAD3/DNA complex. (B) Nuclear extracts from Flag-SMAD3 and SMAD4-Myc-transfected COS-1 cells were used in EMSA and were supershifted with 3 μg of either anti-Flag or anti-Myc antibodies. Note that the anti-Myc antibody does not supershift complex 1.