TGF-β Signaling Cooperates with AT Motif-Binding Factor-1 for Repression of the α-Fetoprotein Promoter

Figure 8

Proposed inhibitory mechanism by which the TGF-β/Smad signaling and ATBF1 cooperatively regulate the activity of the AFP promoter. The distal and proximal AT-motifs in the AFP promoter are bound by ATBF1. Upon TGF-β signaling, the R-Smads/Smad4 complex interacts with ATBF1 to make a repressive complex for the activity of the AFP promoter. However, whether another protein(s) (termed “X”) is essential for the R-Smad/Smad4/ATBF1 complex remains veiled.