PCR for detection of the LN vector in bnx/hu bone marrow and tissues. DNA was extracted from the bone marrow and tissues of mice from experiments 5 and 6, after 9 to 11 months engraftment. Each sample was subjected to PCR to detect the presence of the neo gene. Hybridization with a neo-specific oligonucleotide probe was done to ensure that the product band had been correctly amplified. Tissues that were positive and negative for the presence of the neo gene were amplified as controls in each reaction. The results from one experiment are shown.