Proliferating yeasts maintain a constant cell size distribution via a sequence of specific checkpoints in G1 and/or G2. Populations of mammalian cells can also maintain a constant size distribution as they proliferate, but their reliance on cell-size checkpoints has been unclear. In the April 24 Journal of Biology — published by BioMed Central, a sister company of The Scientist — Ian Conlon and Martin Raff from University College London show that proliferating Schwann cells and yeast cells use different mechanisms to coordinate their growth with cell division (Journal of Biology, 2:7, April 24, 2003).

Conlon (formerly an assistant editor of the Journal of Biology) and Raff used primary rat Schwann cells and observed that they do not require a cell-size checkpoint to maintain a constant cell-size distribution. In contrast with yeasts, both large and small Schwann cells grew at the same rate, which was dependent on...