In SSc patients ETA surface expression was higher than ETB and was not influenced by the treatment with bosentan (ETA: 281.33 ± 43.47 and ETB: 161.33 ± 43.97; P < 0.05 versus ETA: 270.00 ± 28.16 and ETB: 171.33 ± 35.47; P < 0.05). The gene discussed is EDNRB; the disease is systemic sclerosis.