The transgene construct consists of a Moloney murine sarcoma virus LTR (promoter plus enhancer) linked to the rat Map1b light chain cDNA (which is a 3'-end fragment of the MAP1B full length cDNA) fused at the 3'-end to an oligonucleotide encoding the myc-tag and finally linked to a rabbit b-globin intron and poly(A) signal. The transgene construct was injected into the male pronucleus of fertilized CBA/B6 F1 hybrid mouse eggs. (Friedrich Propst, personal communication)