99660-13-6 IM 4-28 L-Threoninamide, D-phenylalanyl-L-cysteinyl-L-tyrosyl-D-tryptophyl-L-lysyl-L-valyl-L-cysteinyl-, cyclic (2-7)-disulfide P-Cttlvc-T Phe-cyclo(cys-tyr-trp-lys-val-cys)thr-NH2 Phenylalanyl-cyclo(cysteinyl-tyrosyl-tryptophyl-lysyl-valyl-cysteinyl)threoninamide RC 121 RC-121