Profibrotic cytokines such as transforming growth factor-beta (TGF-β), platelet-derived growth factor (PDGF), and connective tissue growth factor (CTGF) that are released by immune cells in GVHD can serve as the initial trigger for fibroblast transdifferentiation to myofibroblasts.20 The gene discussed is CCN2; the disease is graft versus host disease.