Rethinking the regulation of cellular metabolism.

Most biologists working today have not considered the problem of how signal transduction events, which commit cells to energetically demanding processes such as growth and division, are connected to cellular metabolism. The primary reason for this is that we have believed for the last 30 or more years that the metabolism of cells is a homeostatic, self-regulating process that does not depend on any extracellular input. The traditional view is that a mammalian cell decides to take up nutrients whenever its bioenergetic and synthetic reserves are depleted. However, a considerable body of evidence now exists that challenges the notion that the nutrient uptake and metabolism of metazoan cells are cell-autonomous.