A particular highlight in the chapters of the book is that MUFAs may have signaling properties that regulate metabolism. For example, a proper ratio of saturated to MUFA contributes to membrane fluidity, and oleate has also been implicated as a mediator of signal transduction, cellular differentiation and metabolic homeostasis. It is also highlighted that SCD-1 repression mediates the metabolic effects of the hormone leptin. Conditional alleles and corresponding tissue-specific knockout mouse models for many of the SCD gene isorfms have provided a wealth of information on not only tissue-specific fatty acid metabolism but also the key transcription factors that regulate SCD expression under a variety of metabolic and genetic backgrounds. The studies described indicate that control of SCD expression occurs via a series of complex signal transduction schemes making SCD one of the most highly studied lipogenic gene families to date.