A mutated twi proximal element (PE) in which the core sequences of the low affinity TD4 and TD5 dl binding sites have been mutated to the optimal sequence to create high affinity sites, followed by twi sequence from -180 to +160bp relative to the transcription start site, are fused upstream of lacZ.
Expansion of expression domain to the 20 ventral-most cells of the embryo (compare to lacZtwi.PE).
