Therefore, to clarify mechanisms underlying this discrepancy, mutations and p53-related, and expression of, cell cycle-related gene products (p53, p21Cip1, p27Kip1, p16INK4A, Mdm2, p14ARF, Bax, Ki-67) were analysed at the single crypt level in UC-associated dysplasia and carcinomas by a novel combination of microdissection, PCR-direct sequencing and immunohistochemistry (IHC). The gene discussed is CDKN1B; the disease is carcinoma.