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. 2007 Jun 25;27(17):6183–6194. doi: 10.1128/MCB.00132-07

FIG. 3.

FIG. 3.

Erbin inhibits Smad-mediated transcriptional activation. (A to E) Erbin inhibits TGFβ signaling but not BMP signaling. HaCaT cells were cotransfected with Myc-Erbin with either the SBE-Luc reporter (A), ARE-Luc reporter (together with Fast-1) (B), or p21-Luc reporter (C and D). Similarly, C2C12 cells were transfected with Myc-Erbin and the Id1-Luc reporter (E). Luciferase activity was measured 20 h after stimulation with TGFβ (A, B, and C) or BMP (D and E). (F) Erbin's inhibition of TGFβ-induced transcriptional activity is independent of MEK inhibition. HaCaT cells were transfected either with SBE-Luc alone or together with Myc-Erbin. Luciferase activity was measured 20 h after TGFβ stimulation in the presence of MEK inhibitor U0126 or the control compound U0124. (G) An ERK inhibitor blocks ERK activation. HEK293T cells were treated with inhibitor U0126 or the control compound U0124 (from the same stock used for panel F) for 2 h. Cells then were stimulated with epidermal growth factor (EGF) (10 ng/ml) for 30 min. Phosphorylation of ERK was examined by Western blotting with phosphospecific ERK antibody (αP-Erk1/2). (H) Erbin inhibits Smad3-LC-mediated transcription activity. HaCaT cells were cotransfected with the SBE-Luc reporter and increasing amounts of HA-Smad3-LC (S3-LC) with or without Myc-Erbin. Luciferase activity was measured 20 h after TGFβ stimulation. RLU, relative luciferase units; WCL, whole-cell lysate; IB, immunoblot.