FN1 and neoplasm: Staining tumors formed by co-injection of PANC1 + CAFs using an antibody that recognizes hFN, but not mouse FN, reveals areas of intense fibrillar hFN staining (Fig. 6A), suggesting that the co-injected CAFs represent a significant producer of tumor stroma in this model relative to the host (i.e., mouse) fibroblasts.