Notum is a protein that plays a crucial role in the regulation of various biological processes, particularly in the context of Wnt signaling. It acts as a negative regulator, meaning it can inhibit the activity of Wnt proteins, which are essential for cell communication and development. In addition to its role in Wnt signaling, Notum is involved in processes such as tissue regeneration and the maintenance of stem cells. Its function is important in both normal physiological conditions and in the context of diseases, including certain types of cancer, where Wnt signaling can become dysregulated.