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Pathophysiology

A significant player in the process is transforming growth factor (TGFβ). This protein appears to be overproduced, and the fibroblast (possibly in response to other stimuli) also overexpresses the receptor for this mediator. An intracellular pathway (consisting of SMAD2 / SMAD3, SMAD4, and the inhibitor SMAD7) is responsible for the secondary messenger system that induces transcription of the proteins and enzymes responsible for collagen deposition. Sp1 is a transcription factor most closely studied in this context. Apart from TGFβ, connective tissue growth factor (CTGF) has a possible role. Indeed, a common CTGF gene polymorphism is present at an increased level in systemic sclerosis.