Fig. 4. Effect of a low TGF-ß1 concentration on Smad1 and Smad2/3 phosphorylation. Keratinocytes from cultures initiated with Adh⁺⁺⁺EGF-R^-/+ cells were plated on glass slides and grown for 72 hours with or without 10 pg/ml TGF-ß1. The degree of Smad1 and Smad2/3 phosphorylation (presence of p-Smad1 and p-Smad2 and 3) was then evaluated in each condition by immunofluorescence and compared by Laser Scanning Cytometry (LSC) analysis. Results from one representative experiment are presented (n=3). Data are expressed as percentages of positive cells and median values of fluorescence (arbitrary units, a.u.) detected in the two culture conditions.