Hsp70 promoter, 5' untranslated region (UTR) and first seven codons are fused to the lacZ coding region, Hsp70 3' UTR sequences are present.
Expression is fully heat-shock-inducible in virtually all cells during all stages, except pre-blastoderm embryos. In third instar larval salivary gland, detectable expression without heat shock.
Fully inducible in virtually all cells and sensitive to silencing by heterochromatin.