These findings, together with the prognostic impact of Dkk-3 inactivation in ALL, the general expression of Dkk-3 in normal blood cells, the emerging role of the Dkk-3 gene in human cancer and the observation that transfection of human osteosarcoma Saos-2 cells with Dkk-3 entails a decrease in the proliferative activity are supportive of Dkk-3 inactivation contributing directly to the clinical behaviour of ALL, at least in a subgroup of patients. This evidence concerns the gene DKK3 and acute lymphoblastic leukemia.