In human colorectal carcinoma with the CIN phenotype, there is a frequent loss of heterozygosity at loci on chromosomes 5q, 17p, and 18q [27], whereas in CPC;Apc mice carrying constitutional, heterozygous, inactivating mutations in the Apc gene, the wild-type Apc allele is inactivated by loss of heterozygosity, indicating that CIN contributes to tumor progression. The gene discussed is APC; the disease is colorectal carcinoma.