Since Siperstein and Fagan (Siperstein and Fagan, 1964) reported the dysregulation of cholesterol synthesis in tumors and tumor-bearing animals, the uncoupling of HMGCR activity from sterol-mediated feedback regulation has been found in diverse tumors, embryonic and differentiating tissues and carcinogen-treated and regenerating liver (Elson et al., 1999). This evidence concerns the gene HMGCR and neoplasm.