Advances in the development of molecular tools for the inducible control of transcription, translation, and protein degradation are the basis for the rapidly emerging design and construction of synthetic gene networks in mammalian cells. In this chapter, we describe such tools and how they can be integrated into a synthetic gene network with desired functionality. The network design and construction process is illustrated in the form of a detailed protocol for the implementation of a logic NOR gate based on an inducible promoter combined with an inducible protein degradation system. © 2012 Springer Science+Business Media, LLC.