The ECM is a three-dimensional network that, besides the main constituent collagen, is composed of other macromolecules, including elastin, fibronectin, glycoproteins, hyaluronic acid, laminin, lysyl oxidase (LOX), proteoglycans, and tenascins, which are upregulated in cancer and thus provide structural, mechanical, and biochemical cues to cells such as cancer cells and CSCs [202]. Here, FN1 is linked to cancer.