From 2007.igem.org

According to the in vitro cross-binding data reported by Kalodimos et al.[], We used [|LacI] and [|LRLa] as the upstream input signals in the first version, and used O11 (the symmetric operator of [|LacI]) and O22(the symmetric operator of [|LacI]) to construct logic promoters. But unfortunately, experimental data show that these two repressor can bind to the relative operator of each other in vivo. All measurements of co-repression based-on these two repressors are abandoned.