I don't know how you missed it Eskaminagaga. From same release 4/12/11
"Sigma has agreed that upon exercise of the option Kraig will have exclusive commercial rights to use Sigma ZFNs in conjunction with the insertion of more than two hundred proprietary spider silk sequences previously licensed by Kraig from a third party into the silkworm genome. Sigma-Aldrich will be creating customized zinc fingers for Kraig's use in its development of spider silk polymers and technical textiles."