Overall, the active concentration at which TCH-165 doubles 20S proteasome activity (EC200 1.5 μM) corresponded well to the effective concentration required to reduce MYC gene transcription (EC50) and induce 50% cell death (CC50) in various cell cultures, and corresponded to the Cmax obtained in vivo and required to inhibit tumor growth. This evidence concerns the gene MYC and neoplasm.