Screen shots of ClustalXeed. The visual dialog boxes showing the powerful graphical user interface (GUI) environment for both parallel- and single-mode computations of multiple sequence alignments. (A) ClustalXeed enables easy iterative refinement of a poorly aligned region (shaded box area) on a new screen mode. (B) The enhanced tree drawing option provides three different scalable, high resolution vector graphics. This option is especially useful for generating phylogenies from large data sets. (C) Thirty-four different, ready-made protein weight matrices are helpful for detecting similarities among divergent or markedly biased sequences.