PCR analysis of hematopoietic progenitor colonies transduced with G1Na and LNL6 retroviral vectors. DNA samples isolated at week 2 posttransduction from 10 representativeneo^R hematopoietic colonies (lanes 2 through 11) from human BM CD34⁺ cells transduced with G1Na on d1 followed by LNL6 on d5 were subjected to PCR analysis using G1Na-specific (a) or LNL6-specific (b) primer pairs. The products of PCR amplification were electrophoresed on 2% agarose gel and visualized on Southern blots using ³²P-labeledneo-specific sequences. While 4 colonies (lanes 2, 4, 5, and 6) showed the presence of both retroviral vectors, 2 colonies each (lanes 7 and 9 and lanes 10 and 11), respectively, showed sequences specific for either LNL6 or G1Na vectors alone. Lane 1 is a negative control. PCR amplification of DNA obtained from 2 colonies (lanes 3 and 8) was not successful.