A 'Modular vector' (MV) regulatory cassette is fused upstream of a wild-type Dronc cDNA. The Dronc coding sequence is tagged at the C-terminal end with both Tag:V5 and the C155-Venus split fluorescent fragment. The MV cassette consists of an mFRT71 cassette containing 5xlexAop regulatory sequences plus a minimal Hsp70 promoter ('Module 1'), an FRT cassette containing 5xUAS regulatory sequences plus a minimal Hsp70 promoter ('Module 2'), and a loxP cassette containing 5xQUAS regulatory sequences plus a minimal Hsp70 promoter ('Module 3'). The use of incompatible recombination sites flanking each regulatory sequence module allows them to be excised singly or in combination depending on the specific recombinase(s) used.