Expression of the hMSH6 mismatch-repair protein in colon cancer and HeLa cells

A phenotype characterised by widespread in-stability of microsatellite sequences in DNA has been reported to occur in 10–15 % of human colon cancers [1, 2]. Microsatellites are stretches of re-peated DNA sequences consisting of mono-, di- or tri-nucleotide repeats. Mono- and di-nucleotide microsatellites are either shorter or longer by a few repeat units in this subset of colon cancers, when compared to those in the DNA of normal tissues. Microsatellite instability (MSI) is caused by a de-fect of the Mismatch Repair (MMR) system, which has evolved to correct errors of DNA polymerases [3, 4]. These enzymes are error-prone and, during DNA replication, they can cause strand misalign-ments with the formation of loops of extrahelica