EDN1 and fibrosarcoma: Similar to fibrosarcomas, MPNST's were also found to have nearly 3-fold increased expression of the ET-1 gene compared to normal schwann cells [20], suggesting that ET-1 upregulation may be a consistent feature of sarcomas in general, and raising the possibility that ET-1 antagonism might be useful in treating MPNST rest pain, though formal in vivo evidence is presently lacking.