PRUNE, the human homologue of the Drosophila gene, is located in 1q21.3, a region highly amplified in human sarcomas, malignant tumours of mesenchymal origin. Human prune (h-prune), a phosphoesterase DHH family appertaining protein, physically interacts with nm23-H1, a metastasis suppressor gene. h-prune is involved in cellular motility and metastasis formation. Metastatic breast cancers were found to overexpress h-prune; h-prune was also found to be highly expressed in colorectal and pancreatic cancers. Hence h-prune is considered useful as a marker for tumor aggressiveness.