UASt regulatory sequences drive expression of the Hsap\TGFB3 open reading frame. The endogenous stop codon is present, thus even though three copies of the Tag:HA tag are present downstream of the ORF, they are not expected to form part of the translated protein. The ORF is flanked by a pair of incompatible FRT sites (FRT5 and FRT2), which allows for future in vivo exchange of either the promoter or tag sequence.