1. Introduction Much progress has been made toward the identification of molecular
pathogenesis of cancers. Several studies have been done to understand cancer related genes including tumor suppressor genes. This class of genes includes many genes which are involved in hereditary and nonhereditary cancers (Haber and Harlow, 1997). Tumor suppressor genes govern a wide range of normal cellular activities such as cell cycle checkpoint and DNA repair which might be deregulated in cancer cells.