Although GFP-negative ftz-f1 mutant cysts (outlined in Figure 5, A–C’) expressed Orb, the levels of Orb protein in ftz-f1 mutant cysts were much lower than in adjacent, less-developed wild-type cysts (Figure 5A; compare arrowhead in the stage 1 wild-type cyst with the outlined stage 3 mutant cyst). The gene discussed is NR5A1; the disease is cyst.