P-element insertion within the 5' regulatory region.
argos[+]/aosp1 is an enhancer of visible phenotype of Scer\GAL4en-e16E, tumΔE1E.UAS
argos[+]/aosp1 is an enhancer of sensillum campaniformium & wing vein | supernumerary phenotype of Scer\GAL4en-e16E, tumΔE1E.UAS
Precise excision of the P-element results in reversion of the mutant phenotype to wild type.