The importance of quality control in the manufacturing industry is obvious — nobody wants to buy substandard goods. In this process, defective components are generally weeded out on the production line to ensure that the end product is up to scratch. Quality control is equally important in cells and, on page 181, Lars Ellgaard and Ari Helenius review the role of the endoplasmic reticulum quality-control system in proof-reading newly synthesized proteins. By preventing misfolded non-native protein conformers from leaving the endoplasmic reticulum, this quality-control system helps to ensure the fidelity of cellular functions.

The control of gene expression is also essential for the normal growth and development of organisms and, in a Review on page 192, Masafumi Muratani and William P. Tansey discuss how the ubiquitin–proteasome system uses proteolytic and non-proteolytic activities to regulate which genes are turned on, and when they are activated.

Finally, this month we include a new type of Perspective article; one that looks at new technologies. In the first of these 'Innovation' articles (page 237), Peter J. Hunter and Thomas K. Borg introduce the Physiome Project, which will use computational methods to model the human body by integrating biochemical, biophysical and anatomical information from cells, tissues and organs. And, in the second article on page 243, Thomas B. Kirkwood and colleagues discuss their project to create a web-based modelling system for ageing. Called BASIS (for Biology of Ageing e-Science Integration and Simulation), this will represent systems at the level of the cell, tissue and organism, and is a concerted effort to integrate theory and data.