In addition, no change in hepatic fibrosis was observed in Mst4 knockout mice as demonstrated by similar labeling for liver collagen IV, fibronectin, Picrosirius Red (stains both collagen type I and type III), and αSMA (a marker for activated hepatic stellate cells, which secrete extracellular matrix proteins) in the two groups (Figure 7A,B). The gene discussed is ACTA1; the disease is Hepatic fibrosis.