ACTA1 and neoplasm: Our observation that αSMA was highly expressed in peritumoral fibroblasts may be due to the autocrine activity of activin A. Activin A secreted at the tumor-stromal interface may also affect immune and endothelial cells by regulating differentiation of macrophage and dendritic cells, conversion of native CD4+ T cells to Foxp3+ Treg cells46, and tube formation of endothelial cells47.