Genetically-engineered spider silk could be used in gene therapy

Genetically-engineered spider silk could be used in gene therapy: "Spider silk is pretty amazing stuff. Pound for pound, it has a tensile strength close to that of steel while being one-fifth as dense, it's tougher than Kevlar, and it can stretch to almost one-and-a-half times its length without breaking. As if that wasn't enough, it now appears that a genetically engineered version of the substance could be used for delivering genes into human cells."