This is a Ph.D. dissertation. The present thesis forms an integral part of the efforts to understand the molecular mechanisms and the biological and clinical significance of increased lipogenesis in tumor cells. In part I, it is explored whether the PI3-kinase/Akt pathway, a signal transduction cascade which is frequently dysregulated and constitutively activated in cancer cells, may contribute to increased lipogenesis. In part II, the authors have tried to gain more insight into the functional significance of tumor-associated lipogenesis by unraveling the nature and fate of newly synthesized lipids in cancer cells. To put these studies in a proper perspective, the authors will provide a more detailed overview of the present understanding of the mechanisms, the role and the clinical significance of increased lipogenesis in human cancer.