To differentiate fibroblasts from vascular smooth muscle cells in the intra-tumor region, we used S100a4-Cre; Ext1f/f; Lsl-tdTomato and control (S100a4-Cre; Lsl-tdTomato) mice, as in the MC38 colon tumor model (Fig 3B). This evidence concerns the gene S100A4 and neoplasm.