Mismatch repair is a cellular process that corrects errors that occur during DNA replication. When DNA is copied, sometimes the wrong nucleotide is inserted, leading to mismatches. The mismatch repair system identifies these errors and removes the incorrect nucleotides, replacing them with the correct ones to maintain genetic stability. This repair mechanism is crucial for preventing mutations that could lead to diseases, including cancer. Key proteins involved in mismatch repair include MLH1, MSH2, and PMS2. These proteins work together to recognize and fix mismatches, ensuring that the genetic information is accurately passed on during cell division.