7-Keto-25-hydroxy Cholesterol, an oxysterol and proposed metabolite of 7-keto cholesterol and 7-dehydro cholesterol, binds to and activates Smoothened (Smo) at the conserved extracellular cysteine-rich domain (CRD) in a reporter assay. Additionally, it enhances the number of EGF high affinity binding sites in normal rat kidney (NRK) cells.