sentences:  This protein complex formed between the 2 sets of heterodimers enables initiation of repair of the mismatch defect.Other gene products involved in mismatch repair (subsequent to initiation by DMA mismatch repair genes) include DNA polymerase delta, PCNA, RPA, HMGB1, RFC and DNA ligase I, plus histone and chromatin modifying factors.Only a minority of sporadic cancers with a DNA repair deficiency have a mutation in a DNA repair gene.