ACTA1 and systemic sclerosis: In parallel, we detected a significant upregulation of genes encoding mesenchymal/myofibroblast markers, including ACTA2 (α-SMA), S100A4 (fibroblast-specific protein-1), COL1A1 and COL1A2 (α1 and α2 chains of type I collagen) in ADSC challenged with SSc sera (p < 0.001 vs. basal and healthy serum-treated ADSC for all genes) (Figure 2).