Addition of a skl 3'UTR.
A tubulin promoter drives expression of EGFP tagged with the micro RNA (mir-2b-2, mir-6 and mir-11) target sequences from the skl gene 3' UTR (GGCUCCUAAAGCGCAACUUGUGAUU and ACUUUGGAUAAGCGCAAAUGUGAUA) in its 3' UTR.