Fig. 4. Regulation of Dan by Hth and Dll. (A) Dan expression in hth^c1 mutant clones. (Boxed region) The three channels are shown separately at right. The clone was marked by the absence of GFP (green) and Hth protein (red). (B) Dan expression in Dll^SA1 mutant clones. The three channels are shown separately on the right of the region indicated by an arrowhead. The clone was marked by the absence of GFP (green) and Dll protein (red). Other Dll mutant clones sorted out towards the edge of the Dan domain (arrows). (C) Ectopic expression of Dan (blue) in the distal leg when Hth was misexpressed (Hth expression was marked by co-expression of GFP. Hth-expressing cells sort out from the distal region by this stage (see Wu and Cohen, 1999). Dan expression shown alone in the inset. (D) Ectopic expression (arrow) of Dan (green) in the proximal leg [overlapping Hth (red)], when Dll was misexpressed (Dll not shown).