MSH3 and colonic neoplasm: By transfecting into colon cancer cells with various DNA mismatch repair backgrounds or by knockdown of MSH3, the authors demonstrate that MSH3 loss is responsible for ongoing tetranucleotide frameshifts, with rates of ~18 × 10−4 to 34 × 10−4 mutations/cell/generation, compared to MSH6-deficient cells at rates of ~0.8 × 10−4 mutations/cell/generation [26].