This month's release of Cold Spring Harbor Protocols focuses on cloning, X-chromosome inactivation, stem cells, and embryogenesis.

Cold Spring Harbor Protocols (http://www.cshprotocols.org) is an online resource of methods used in a wide range of biology laboratories. It is structured to be highly interactive, with each protocol cross-linked to related methods, descriptive information panels, and illustrative material to maximize the total information available to investigators. Each protocol is clearly presented and designed for easy use at the bench-complete with reagents, equipment, and recipe lists. Life science researchers can access the entire collection via institutional site licenses, and can add their suggestions and comments to further refine the techniques.

The protocols for the June issue are freely available here. Featured free-access articles this month are: Chromatin Immunoprecipitation (ChIP) on Unfixed Chromatin from Cells and Tissues to Analyze Histone Modifications and Xenopus laevis Keller Explants.