The inserted transgenic construct contains a human vasopressin promoter region adjoined to a 1.9 kb fragment of a v-src gene from the Schmidt-Ruppin A strain of RSV. Southern blot analysis indicated that a single copy of the construct integrated into the genome of founder mice. Mapping data indicated that a complex rearrangement involving 6.3 cM of flanking genomic DNA had taken place at the transgene insertion site. The DNA was not deleted nor simply inverted and involved at least 4 breakpoints. (J:62376)