Ambion® IPTG (Isopropyl-beta-D-thiogalactoside) is an inducer of the lac operon and is frequently used in conjunction with X-GAL to determine the lac phenotype of recombinant plasmids or phage. IPTG is also used to induce the expression of cloned genes that are under control of the lac operon. Supplied in one bottle containing 2 g.