REN and Hypertension: Two decades ago, new strain of inbred transgenic rats with inducible hypertension [strain name, TGR (Cyp1a1–Ren-2)] was generated using the cytochrome P-450 promoter, Cyp1a1, to regulate the expression of the mouse Ren-2 renin gene (Kantachuvesiri et al., 2001).