MLH1 and cancer: Immunohistochemical staining revealed overexpression of epidermal growth factor receptor (EGFR), which plays an important role in colon cancer oncogenesis and represents an important target for cancer therapy.4 However, no defects were found for the deoxyribonucleic acid (DNA) mismatch repair system, that is, the MLH1 (human mutL homolog 1), MSH2 (human mutS homolog 2), MSH6 (human mutS homolog 6), and PMS2 (human postmeiotic segregation 2) proteins (Figure 3D1–D5).