Organization of the MGS gene cluster (a) and proposed biosynthetic pathway for iso-MGS and its biosynthetic relationship to MGS and DGN A, 13-epi-DGN A, and B (b) (Lim et al. 2009). ACP acyl carrier protein, AMT aminotransferase, AT acyltransferase, DGN dorrigocin, DH dehydratase, iso-MGS iso-migrastatin, KR ketoreductase, KS ketoacyl synthase, MGS migrastatin, MT methyltransferase, PKS polyketide synthase, TE thioesterase, ? domain of unknown function