PDGF functions as a primary mitogen and chemoattractant for cells of mesenchymal origin. Members of the PDGF family play an important role during embryonic development and contribute to the maintenance of connective tissue in adults. Deregulation of PDGF signalling has been linked to atherosclerosis, pulmonary hypertension and organ fibrosis. Elevated expression of PDGF and its receptors has been found in scleroderma skin and lung tissues. There is evidence for a TGF-beta and IL-1alpha-dependent autocrine PDGF-A/PDGFRalpha signalling loop in scleroderma skin and lung fibroblasts, suggesting that a cross-talk between TGF-beta and PDGF pathways may regulate chronic fibrosis in scleroderma.