Expression of a lacZ reporter is under the control of a fragment of Prm intron 7 including both the 'AB' element (-1469 to -1343 bp to the 3' end of intron 7) and the BF element (-1469 to -1343 bp from the 3' end of intron 7) upstream of an 'Hsp70' minimal promoter. (Curator comment: coordinates from FBrf0135243).