H-prune, a new cyclic nucleotide phosphodiesterase, binds to nm23-H1, a metastasis suppressor protein. The overexpression of h-prune in the MDA-MB-435 breast carcinoma cell line causes a substantial decrease of cAMP, and an increase in cellular motility. This latest effect is correlated both to the h-prune phosphodiesterase activity and to the interaction between h-prune and nm23-H1 proteins. Understanding the molecular changes in tumor cells with an increased level of expression of h-prune might shed light on motility processes, which are the driving forces of the cells to move away from the primary tumor and to become metastatic. This report overview genes and pathways influenced by h-prune overexpression in a conventional breast cancer cellular model.