We all have our 'tools of the trade' — maybe a pipette for a cell biologist, or a red pen for an editor. And, it's not just humans that have such tools. More primitive organisms, such as bacteria, also have a selection of tools that they use for their trade. For example, in the Review on page 742, Guy R. Cornelis discusses the type-III secretion system and the injectisome 'tool' that some pathogenic bacteria use to inject proteins into the cytosol of eukaryotic cells to 'anaesthetize' or 'enslave' them. Furthermore, in addition to their own tools, bacteria can also use host proteins to get their own way. On page 753, Gary Thomas reviews furin — an enzyme that can activate several bacterial toxins, as well as numerous pathogenic viruses. It's hard to believe that an enzyme that is essential for embryogenesis, can also lead to deadly diseases in adults.

Sometimes, though, a single type of tool can have several trades. In a Review on page 767, Rolf Jessberger discusses the 'structural maintenance of chromosomes' (SMC) proteins. Although these proteins share the same characteristic design and configuration of protein domains, they have a variety of functions in chromosome dynamics, such as in sister-chromatid cohesion, chromosome condensation, gene dosage compensation, and DNA repair and recombination.

Finally, Nature Cell Biology and Nature Reviews Molecular Cell Biology are pleased to announce the launch of a competition. Cell biology is renowned for the beautiful images it produces, so why not enter your images in our 'Cell of the Month' competition? From January 2003, one winning image will be published in both journals each month, and you can use our online submission facility to submit your entries to us now (http://www.nature.com/ncb/esubmission/). Go on, show us what you've produced with your tools of the trade!