In addition, activated Smad signals stimulated subsignals, such as to levels of type I collagen (Col1), α-smooth muscle actin (Acta2/α-SMA), and fibroblast-specific protein 1 (Fsp1/S100A4), related to collagen accumulation and lung fibrosis [64]. The gene discussed is ACTA2; the disease is pulmonary fibrosis.