poly polymerase - 1 is a central signaling enzyme in a cell nucleus . parp - 1 is a target for the development of radio and chemo sensitizing agents in cancer treatment as well as providing protection from stroke . an sh3 domain and an sh3 ligand domain have now been discovered on the parp - 1 protein . these domains are involved in parp - 1 activation . this discovery makes possible the use of bioinformatics tools for the design of new drugs and strategies for drug target selection , specifically targeting the parp - 1 enzyme .