Methylation of the Dkk-3 promoter region was associated with loss of Dkk-3 gene expression in neoplastic cells and this expression was restored after exposure to the demethylating agent 5-AzaC, indicating that hypermethylation is a major mechanism by which Dkk-3 expression is silenced in ALL cells. This evidence concerns the gene DKK3 and acute lymphoblastic leukemia.