DJ-1 was cloned from HeLa cell cDNA library as a novel oncogene which transforms NIH3T3 cells in cooperation with Ras. DJ-1 expresses in various tissues. The expression of DJ-1 is induced by growth signals and translocated from cytoplasm to nuclei during the S phase, although nuclear localization signals reported are not present in the DJ-1 cDNA. DJ-1 has transforming activity on mouse NIH3T3 cells by itself and a stronger activity in cooperation with Ras. DJ-1 is suggested to be a novel mitogen-dependent oncogene product involved in Ras-related signal transduction pathway.