Figure 1.

Stable expression of functional Smad4-MER in transfected clones of the breast cancer line MDA-MB-468. (A) Immunoblots confirm the expression of full-length Smad4-MER, MER, and 100T-Smad4-MER. (B) Fusion proteins exhibit the expected activity with SBE-containing transcriptional reporters. Stable clones were transfected with 6SBE-Luc (S) or 3TP-lux (T) before being treated for 20 h with (+) or without (−) 100 nM 4-OHT. pCMVβ was cotransfected to normalize for transfection efficiencies. Luciferase and β-galactosidase activities were determined. The luciferase activities in the absence of 4-OHT are arbitrarily set at 1. The means of three independent experiments are shown. Bars represent SE.