Abstract: The present invention relates generally to the field of human genetics. Specifically, the present invention relates to methods and materials used to isolate and detect a human tumor suppressor gene, termed RASSF1 herein. More specifically, the invention relates to the analysis of the RASSF1 gene and its use in the diagnosis of predisposition to cancer. The invention also relates to the prophylaxis and/or therapy of cancer associated with the RASSF1 gene. The invention further relates to the screening of drugs for cancer therapy. Finally, the invention relates to the screening of the RASSF1 gene for methylation, loss of heterozygosity or mutations, which are useful for diagnosing the predisposition to cancer.