NRP1 and colorectal cancer: Deleted in colorectal cancer is a transmembrane receptor of the immunoglobulin superfamily highly expressed in spinal commissural neurons (Keino-Masu et al., 1996), the retina (Gad et al., 2000; Johansson et al., 2001), and many projection neurons of the fore- and midbrain during embryonic development (Shu et al., 2000).