Fig. 1. Expression of TGFβ receptors and Smads in L₆E₉ cells. L₆E₉ cells were serum starved for 24 hours before TGFβ1 treatment. (A) The expression of ALK1, ALK5 and TβRII from control (C) or 500 pM TGFβ1-treated (T) cells (24 hours) was analyzed by RT-PCR and western blot. (B) Myoblasts were stimulated with TGFβ1 for the indicated time periods. Total proteins extracts were analyzed by western blot with anti-phospho-Smad1, anti-phospho-Smad2, anti-Smad2/3 and anti-Smad4 antibodies. Loading controls included GAPDH, β-actin and tubulin. A representative blot from three independent experiments is shown. (C) Immunofluorescence of Smad1/5, Smad2/3 and Smad4 in L₆E₉ cells untreated or treated with TGFβ1 for 24 hours.