Since the CDC20-1 DsiRNA led to >80% growth inhibition in MDA-MB-435WT cells in vitro (more so than the CDC20 siRNA from library screens), we further evaluated its efficacy in vivo by injecting DsiRNA/PEI-LA complexes to breast cancer xenografts weekly and bi-weekly subcutaneously in the vicinity of tumor. The gene discussed is CDC20; the disease is breast cancer.