FN1 and cancer: The chemoattractive functions of netrin-1 are mediated by “deleted in colorectal cancer” (DCC) family of proteins (UNC-40 in C. elegans, Frazzled in Drosophila), characterized by four immunoglobulin (Ig) and six fibronectin (Fn) type III repeats in their extracellular domains [5,16,17,24].