• starting from 4 months of age, mutants present with highly metastatic tumors originating in the adrenal medulla or sympathetic ganglia

• metastasis into liver, lungs, and para-aortic lymph nodes

• starting from 4 months of age, mutants present with highly metastatic tumors originating in the adrenal medulla or sympathetic ganglia that resemble human infant neuroblastoma

• tumor incidence is 18%

• most tumors typically are bilateral adrenal tumors with multiple metastatic nodules in liver, lungs, and para-aortic lymph nodes

• most tumors typically are bilateral adrenal tumors with multiple metastatic nodules in liver, lungs, and para-aortic lymph nodes

• some mutants die from intra-abdominal bleeding from spontaneously ruptured, highly vascularized adrenal tumors

• 4-week old mutants do not have measurable levels of antibodies against SV40 Tag, but by 5 months of age, they show a humoral immune response against the transgene product, indicating a lack of immunological tolerance to Tag

• adrenal glands with no evidence of tumors show lymphocytic infiltrations, signs of medullary cell destruction and hemorrhagic areas at the cortico-medullary border