(A) The wild-type and mutated eGFP gene segments with the target codon located in the center of the sequences are displayed in green and red respectively. The nucleotide targeted for exchange is emphasized in bold and underlined. (B) Phosphorothioate modified, end protected (denoted with *) 72NT, a 72-mer which is used to target the non-transcribed (NT) strand and 72T, which directs exchange on the transcribed strand (T) of the mutated eGFP gene as shown. Also depicted is the sequence of the unmodified ssODN, 72NT-U, which is equivalent to the 72NT without phosphorothioate end modifications.