Expression pattern of the dual specificity phosphatase 5 (dusp5) as analyzed by in situ hybridization. Anterior is to the left in all panels. (A)The 3-somite stage. A flat mount of the deyolked embryo. dusp5 is expressed in presumptive endothelial precursor cells, which form 2 bilateral stripes of cells that merge in the posterior. The 15-somite stage: (B) lateral view and (C) dorsal view. dusp5 is expressed in 2 bilateral stripes of cells within the lateral mesoderm in the anterior (arrow in B) and middle/posterior (arrowhead in B) parts of an embryo. In addition, a stripe of dusp5-expressing cells is apparent at the midline and extends through the middle and posterior parts of an embryo (arrowhead in C). (D) The 26-hpf stage. dusp5 expressed in all endothelial cells of the axial, head, and intersomitic vessels. The 52-hpf stage: (E) lateral view, (F) ventral view, and (inset) rostral view. dusp5 is expressed in a subset of nonvascular cells in the forebrain (arrowhead).