Fibronectin
Fibronectin is an extracellular matrix protein that helps cells attach to the matrix by acting as a "linker" that binds to a cell-surface integrin molecule on one end and to a matrix component (such as collagen) on the other end. Alberts, Bray, Hopkin, Johnson, Lewis, Raff, Roberts, Walter 2014, Essential Cell Biology, 4th edn, Garland Science, New York.