An Hsp70 promoter drives expression of FLP recombinase.
All flies bearing Scer\FLP1hs.PG become mosaic at 38.5oC, a lower temperature reduces the number of mosaics.
Golic and Lindquist
There is a low level of constitutive expression. Recombinase is active in the somatic cells and the germline producing white-eyed and dark red-eyed progeny.
Transient transfection assay in DH33 cultured cells.