Figure 3 Overexpression of serum response factor (SRF) in either oesophageal epithelial cells or fibroblasts is sufficient to induce myofibroblast phenotype. Both Het1A and Rat1‐R12 cells were transfected with either SRF+ plasmid or plasmid vehicle (control) and stained for SRF (counterstained with haematoxylin), smooth muscle (SM) α‐actin (counterstained with propidium iodide) or G‐/F‐actin (Oregon Green‐conjugated phalloidin and Texas Red‐conjugated deoxynuclease I). Overexpression of SRF (SRF+) induced SM α‐actin expression and actin stress fibre formation in both (A) Rat1‐R12 cells and (B) Het1A cells.