The present invention is directed to an isolated miR-206 target site, comprising or consisting of a nucleic acid sequence with a sequence identity of at least 80% compared to wild type miR-206 target site with SEQ ID No. 1, characterized in that the nucleic acid sequence comprises at least one nucleotide substitution at a position from nucleotide 2 to 8 and/or at least one nucleotide substitution at a position from nucleotide 12 to 16 of SEQ D No. 1, wherein the nucleotide positions of SEQ ID No. 1 are numbered from the 3′- to the 5′-end as well as to an expression cassette, vector and pharmaceutical composition comprising at least one isolated miR-206 target site of the invention.
