Fig. 7.

FLNB stabilizes i-Smad and Smad1 binding, inducing Smad1 degradation. Our model illustrates that under wild-type conditions (a), the Smad1 linker region is phosphorylated by TGFβ-activated ERK, which tags the molecule for degradation through the recruitment of Smad6, whose interaction with Smad1 is stabilized by FLNB. In the absence of FLNB (b), linker phosphorylated Smad1 is degraded less efficiently and allowed to induce increased transcription of nuclear targets