sentences:  Defects in mismatch repair, found in about 13% of colorectal cancers, are much more frequently due to deficiency of MLH1 than deficiencies of other DNA mismatch repair proteins.The seven DNA mismatch repair proteins in humans are MLH1, MLH3, MSH2, MSH3, MSH6, PMS1 and PMS2.In addition, there are Exo1-dependent and Exo1-independent DNA mismatch repair subpathways.