ACTA1 and neoplasm: SDF-1 production is the result of activation of HSCs, which are thought to be progenitors to α-smooth muscle actin (α-SMA)-positive myofibroblasts [21] This phenotype is usually a marker for cancer-associated fibroblasts, which are tumor-activated forms of fibroblasts that secrete matrix proteins such as collagen, and can enhance the metastatic properties of the tumor [22].