ACTA1 and neoplasm: We found that after three weeks, the number of co-injected GFP-tagged human fibroblasts comprised roughly 20% of the tumor stroma as judged by co-localization of GFP and the fibroblast stromal marker alpha-smooth muscle actin (α-SMA) (Figure S2), but the relative contribution steadily declined from week 3 to week 8, although the GFP-fibroblasts never completely disappear.