In this study, we investigated the true frequency of ST7 gene mutations by examining 48 primary colorectal cancers, 48 primary gastric cancers that frequently show LOH on 7q31 (Nishizuka et al, 1997), and 48 primary hepatocellular carcinomas that show high-level expression of the ST7/RAY1 gene (Vincent et al, 2000; Zenklusen et al, 2001). The gene discussed is ST7; the disease is colorectal cancer.