Methylenetetrahydrofolate reductase C677T polymorphism in patients with gastric and colorectal cancer in a Korean population oleh Hwang Jun, Shim Hyun, Choi Jin-Su, Piao Jin-Mei, Song Hye-Rim, Kim Hee, Kweon Sun-Seog, Shin Min-Ho, Cui Lian-Hua, Kim Hyeong-Rok, Park Young-Kyu, Kim Soo-Hyun