●Border crossings. Ager, A. Nature 13 February (2003) This News & Views article looks at how inflammatory cells leave blood vessels to repair injured tissues; new data indicate that the invagination and expulsion of endothelial membranes might be a crucial mechanism.

●Mannose 6-phosphate receptors: new twists in the tale. Ghosh, P., Dahms, N. M. & Kornfeld, S. Nature Reviews Molecular Cell Biology March (2003) New evidence indicates that one of the two mannose 6-phosphate receptors that deliver newly synthesized acid hydrolases from the trans-Golgi network to the endosomal–lysosomal system can also regulate cell growth and motility, and that it might even act as a tumour suppressor.

●siRNAs knock down hepatitis. Zamore, P. D. & Aronin, N. Nature Medicine March (2003)

●Tuning the immune system: competing positive and negative feedback loops. Mueller, D. L. Nature Immunology March (2003)

●Cancer T-cell therapy expands. Becknell, B. & Caligiuri, M. Nature Medicine March (2003)

●A case of mistaken identity. Watford, W. T. & O'Shea, J. J. Nature 13 February (2003) There is much evidence that IL-12 has an important role in autoimmunity; this News & Views article describes a new paper looking at the role of the close relative IL-23.

●Mice, microbes and models of infection. Buer, J. & Balling, R. Nature Reviews Genetics March (2003) This article describes how marked differences between inbred strains of mice in terms of their response to pathogen infection can be exploited to analyse the genetic basis of infections.

●Memory lanes. Badovinac, V. P. & Harty, J. T. Nature Immunology March (2003) This News & Views article looks at the lineage relationships between central and effector memory T cells.