Two transgenic fragments were co-injected to generate the mouse line. One fragment contains a 3 kb human BEST1 promoter fragment driving expression of the tetracycline-inducible transactivator rtTA and the SV40 polyA sequence. The second fragment consists of the tetracycline-responsive regulatory element (tetO) and human cytomegalovirus immediate early enhancer (hCMV) controlling expression of a translationally optimized cre sequence followed by the mouse metallothionein (Mt1) polyadenylation signal. After co-injection into zygotes, 10 founders were obtained with co-integration of both fragments into a single chromosome being observed in all founders. One line demonstrating substantial activity in Muller glial cells was characterized further.