Butera JA, Larsen BD, Hennan JK, et al. Discovery of (2S,4R)-1-(2-aminoacetyl)-4-benzamidopyrrolidine-2-carboxylic acid hydrochloride (GAP-134)13, an orally active small molecule gap-junction modifier for the treatment of atrial fibrillation. Journal of medicinal chemistry. 2009;52(4):908–11. Available at: http://www.ncbi.nlm.nih.gov/pubmed/19175320