FN1 and neoplasm: The bottom line for the role of macrophages and their secretion of FN eventually organized into FN matrices in pro-tumor TMEs is that any type of macrophages belonging to TAMs should comply with the criteria in which macrophages are potent to persistently secrete FN and render FN matrix deposition in TMEs in favoring tumor growth and malignant development when endogenous FN expression is downregulated in tumor cells.