 "DCC" held a controversial place as a tumour suppressor gene for many years, and is well known as an axon guidance receptor that responds to netrin-1.More recently DCC has been characterized as a dependence receptor, and many hypotheses have been put forward that have revived interest in "DCC"'s candidacy as a tumour suppressor gene, as it may be a ligand-dependent suppressor that is frequently epigenetically silenced.Early studies of colorectal tumours found that allelic deletions of segments of chromosome 18q occur in a very high percentage of colorectal cancers.