Imprecise excision of the progenitor insertion, resulting in a deletion removing part of vtd (including exons 1 and 2).
Expression of Zzzz\NIaScer\UAS.T:SV5\V5,T:SV40\nls2 under the control of Scer\GAL4F4 (by heat-shock to inactivate Scer\GAL80ts.αTub84B) in a vtdex15 mutant background results in a drastic reduction of salivary gland chromosome puffing at band 74. Puffs at band 75 were little affected 2 hours after expression was induced, although puffing was reduced by 4 hours after expression.
vtdex15 is rescued by vtd550TEV.tub.Tag:CS(TEVp),Tag:MYC