Fig. 4. Response of EE4-lacZ to E(spl)VP16 variants. All panels show wing disks carrying one copy of the EE4-lacZ reporter. (A) Wild type. (B) omb-Gal4; UAS-E(spl)m7VP16. Note the intense staining in three proneural clusters: dorsal radius (white arrow), wing margin (arrowhead) and ventral radius (black arrow). The extent of the omb-Gal4 expression domain is visualized in Fig. 5C-E. (C) omb-Gal4; UAS-E(spl)mVP16. No activation is observed. (D) UAS-E(spl)m7VP16; pnr-Gal4. In addition to intense staining in the SC (white arrowhead) and DC (black arrowhead) proneural clusters, dispersed individual cells are expressing EE4-lacZ. (E) sc^10-1/Y background essentially abolishes EE4-lacZ activity. (F) sc^10-1/Y; UAS-E(spl)m7VP16; pnr-Gal4. The intense response of EE4-lacZ observed in D is absent due to absence of Ac and Sc. (G) omb-Gal4; UAS-sc. Note weak and somewhat patchy response of EE4-lacZ to uniform expression of Sc. (H,I) omb-Gal4; UAS-sc UAS-E(spl)m7VP16. Note a more uniform and much more intense response. H is under-stained, whereas I is stained to the same extent as G. The notum proneural clusters (top of each panel), where omb-Gal4 is not expressed, can be used to judge the extent of color development in A-C and G-I.