CLUSTAL W Multiple Sequence Alignment Program ClustalW was written by Des Higgins (now at University College, Cork, Ireland) (des@chah.ucc.ie), Julie Thompson (julie@IGBMC.u-strasbg.fr), Toby Gibson, (Gibson@EMBL-Heidelberg.DE), and Franc'ois Jeanmougin (pingouin@igbmc.u-strasbg.fr). It is a complete rewrite and upgrade of the Clustal and ClustalV packages. which were developed by Des Higgins. New features include the ability to detect read different input formats (NBRF/PIR, Fasta, EMBL/Swissprot); align old alignments; produce phylogenetic trees after alignment (Neighbor Joining trees with a bootstrap option); write different alignment formats (Clustal, NBRF/PIR, GCG, PHYLIP); full command line interface. It is described in the following papers: Thompson, J.D., D. G. Higgins and T. J. Gibson. 1994. CLUSTAL W: improving the sensitivity of progressive multiple sequence alignment through sequence weighting, positions-specific gap penalties and weight matrix choice. Nucleic Acids Research 22: 4673-4680. Higgins, D. G., J. D. Thompson, and T. J. Gibson. 1996. Using CLUSTAL for multiple sequence alignments. Methods in Enzymology 266: 383-402. WWW: http://www-igbmc.u-strasbg.fr/BioInfo/ClustalX/Top.html