A mutated fragment from downstream of the Su(H) gene (the "Autoregulatory Socket Enhancer" - "ASE") is fused upstream of a minimal Hsp70 promoter driving expression of a nuclear-eGFP (Avic\GFP). Nucleotide substitution: single base pair mutation in each Su(H) protein binding site in the Autoregulatory Socket Enhancer (ASE).