The coding sequence for improved cre recombinase was split into two complementary halves. For this transgene construct, the n-terminal half of the cre gene encoding for amino acids 19-59 was fused on its 5' end to an element encoding the coiled-coil leucine zipper domain of the yeast transcription factor GCN4. A Flag tag was also included on the 5' end of the fused construct. This construct was placed under control of the murine Plp1 promoter to drive expression in oligodendrocytes. When this transgene is co-expressed with a transgene that expresses the c-terminal half of icre fused to a leucine zipper domain, the leucine zippers force dimerization resulting in a functional cre recombinase. This line is one of three lines created (A,C,D).