FN transmits ECM signals to stimulate mammary epithelial cells to lose their growth-arrested polarized characteristic, acquire tumor-like behavior, proliferate excessively, and eventually form a disturbed acinar structure in three-dimensional culture10, whereas anti-FN antibodies induce T4-2 tumorigenic cells to form an organized polarized acinar identical to normal breast epithelial cells11. This evidence concerns the gene FN1 and neoplasm.