UAS regulatory sequences drive expression of TBSV\P19 which is tagged with a nuclear localisation signal (Tag:NLS(tra)) and with Tag:FLAG.
Expression of Zzzz\p19Scer\UAS.T:nls5,T:Zzzz\FLAG under the control of Scer\GAL4Act5C suppresses the position effect variegation of the Sb1 allele that is seen in the T(2;3)SbV chromosome.