In addition, with F1 ApcMin/+ mice, it is feasible to study the loss of heterozygosity (LOH) in intestinal tumors using polymorphic markers (e.g. microsatellite loci), and indeed, a radiation-specific LOH pattern involving the Apc locus has been found in tumors that developed after irradiation [14–16]. The gene discussed is APC; the disease is intestinal neoplasm.