, R3 is a hydrogen atom or a methyl radical, R4 is a hydrogen atom or a methyl radical and X is a Proton...http://www.google.com/patents/US4829087?utm_source=gb-gplus-sharePatent US4829087 - Utilization of cysteine derivatives or salts thereof to enhance insulin secretion of the islets of langerhans of the pancreasAdvanced Patent SearchPublication numberUS4829087 APublication typeGrantApplication