APC and neoplasm: The average size of the proliferative zone of nonneoplastic crypts from tumor-free Apc+/Min-FCCC mice was 44 ± 4% (Mean ± S.E.M.), whereas the average size of the proliferative zone of nonneoplastic crypts from tumor-bearing Apc+/Min-FCCC mice was 37 ± 2% (Mean ± S.E.M.).