Clonality analysis by linear amplification–mediated PCR (LAM-PCR). Genomic DNA was isolated from peripheral-blood leukocytes of 6 dogs at 2 time points (6 and 12 months after infusion) and subjected to LAM-PCR to examine clonality of retroviral insertions. The presence of a band likely indicates a unique insertion site. Samples were electrophoresed on a Spreadex gel and photographed by a digital camera. M indicates marker; bp, base pairs.