Emerging roles of the ribonucleotide reductase M2 in colorectal cancer and ultraviolet-induced DNA damage repair

Figure 1 Immunohistochemical analysis of ribonucleotide reductase M2 expression in surgical specimens of tumor tissues or adjacent normal mucosa from patients with colon cancer. A: Normal colorectal mucosa without ribonucleotide reductase M2 (RRM2) expression. This case was considered RRM2-negative; B: Lower RRM2 expression in colorectal cancer (CRC); C-E: High RRM2 expression in CRC; F: Lymph node metastasis of CRC with RRM2 overexpression (original magnification × 20).