FIGURE 1.

CDDO-Im extends TGFβ-dependent Smad2 phosphorylation independently of Smad2 phosphatase activity. Rat2 (A), COS-7 (B), or C2C12 (C) cells were incubated with 0.5 mm TGFβ for 30 min in the absence or presence of 1 μm CDDO-Im, washed, and incubated in media containing Me₂SO (DMSO) (Control), 1 μm CDDO-Im, 10 μm SB431542, or both compounds (CDDO-Im + SB431542) at 37 °C for an additional 1 or 4 h prior to lysis. One hundred micrograms of cell lysates were then processed for SDS-PAGE and immunoblotted with anti-phosphospecific Smad2 (α-P-S2) or Smad2/3 (α-S2/3) antibodies. The bands corresponding to phosphoserine-modified Smad2 (P-S2) and Smad2 (S2) are indicated. Representative blots from four experiments are shown.