CPYPP is a cell-permeable small molecule inhibitor that selectively targets the DHR-2 domain of DOCK2, blocking its Rac1-GEF activity with an IC50 of 22.8 µM. It also inhibits related DOCK family members DOCK180 and DOCK5. This compound is a valuable research tool for studying Rac1-mediated signaling in immune cell migration and cancer metastasis in both cellular and animal models.