Excision of the progenitor insertion, resulting in a deletion that uncovers Vrp1 and five additional proximal transcription units.
Myoblast fusion is significantly compromised in Df(2R)Vrp1D30; Df(3L)BK9 double mutants. There is a greater percentage of hemisegments with a reduced number of nuclei in the double mutants than there is in the single mutants.
Myoblast fusion is blocked at the precursor stage in Df(2R)Vrp1D30 mutant embryos.