NTN1 and neoplasm: Because netrin-1 and its receptors have already been reviewed for their role in neuronal guidance (Tessier-Lavigne and Goodman, 1996; Mehlen and Mazelin, 2003; Mehlen and Fearon, 2004), we will mainly describe here the implications of netrin-1, DCC and UNC5H in apoptosis and consider the consequences on tumour escape mechanisms.