Figure 2.

The down-regulation of SMAD signaling by retroviral transduction inhibits TGF-β–mediated responses. (A) Retroviral infection of the GFP cDNA demonstrates the high transduction efficiency of the NMuMG cells. GFP-retrovirus infected cells were observed by phase contrast and epifluorescence microscopy. (B) Expression of FLAG-tagged Smad3 or Smad7 was detected in retrovirally transduced NMuMG by immunoblotting for the epitope tag. (C) Cells stably transduced with GFP (open bar), Smad3 (gray bar), and Smad7 (closed bar) retrovirus were treated with TGF-β for 24 h and assayed for 3TP-Lux reporter activity (left) and thymidine incorporation (right).