In Vitro: ZAP-70 is a critical molecule in the transduction of T cell antigen receptor signaling and the activation of T cells. Upon activation of the T cell antigen receptor, ZAP-70 is recruited to the intracellular ζ-chains of the T cell receptor, where ZAP-70 is activated and colocalized with its substrates. Inhibitors of ZAP-70 could potentially function as treatments for autoimmune diseases or organ transplantation. ZAP-180013 disrupts the interaction between ZAP-70 and the T cell antigen receptor. The IC50s in both FP and TR-FRET assays for ZAP-180013 are 9.6 μM and 16.841 μM, respectively.