Scer\FRT-mediated recombination between the two progenitor insertions has resulted in the deletion of the genomic sequence between them.
Df(1)rush4 flies that also carry sta+t4.4 are homozygous viable and fertile, demonstrating that rush is an inessential gene.
Homozygous Df(1)rush4, sta+t4.4 cells do not show defects in endosomal compartments.