They are located within a critical region at 3p21.3 and have two main splicing isoforms RASSF1A and 1C. The expression of the longer isoform, RASSF1A, is lost in many tumor lines and primary tumors by promoter methylation, while RASSF1C remains unmethylated [2-11]. This evidence concerns the gene RASSF1 and neoplasm.