Since BALF fibroblasts in SSc and mild asthma display increased migration and express important myofibroblast markers such as α-SMA and ED-A fibronectin, the differential protein expression profile between the two BALF fibroblast groups were studied by using 2-DE and MALDI-TOF-TOF to reveal factors that may account for the distinct fibrotic processes in these disorders. The gene discussed is ACTA1; the disease is systemic sclerosis.