Dr. Shah aims to elucidate structural details of the signaling enzyme ZAP-70, found primarily in immune T cells. Expression of ZAP-70 in other immune cells, B cells, however, is associated with chronic lymphocytic leukemia. Furthermore, loss of ZAP-70 function causes severe combined immunodeficiency; an impaired immune system can increase a patient's susceptibility to tumor development. His research on ZAP-70 structure and function will help understand how this enzyme differs from related signaling enzymes, thereby laying the groundwork for the development of ZAP-70-specific therapeutics.