Expression-based classification map for primary site determination. A probability surface shown as a pseudo-color map was estimated for each cancer type (ovarian shown on cover) and individual clinical samples were projected onto the map according to their positions by self-organizing map. The highest probability (1) is shown in red and lowest (0) in blue. Iso-probability curves for all carcinoma types are outlined in the article by Buckhaults et al. on p. 4144 of this issue.