Cre cDNA was inserted into a Plp1 promoter cassette consisting of exon 1 and intron 1 of the mouse Plp1 gene. The transgene construct was microinjected into 1-cell embryos. 6/29 founders were positive for the transgene and 2 showed successful germline transmission. RT-PCR indicated that Line F633 was expressed solely in the spinal cord, cerebellum, and cortex at P4 and P28. (J:172435)