PCR amplification of genomic DNA isolated from individualneo^R hematopoietic colonies transduced with G1Na (lanes 3, 4, and 6) and LNL6 (lanes 8, 9, and 11) vectors. Samples were subjected to 30 cycles of amplification using primer pairs specific for G1Na (lanes 4 and 8), LNL6 (lanes 3 and 9), or both (lanes 6 and 11). Ethidium bromide–stained products of 829-bp and 481-bp DNA sequences indicate specific amplification by G1Na- and LNL6-specific primers, respectively. Molecular weight markers were loaded in lane 1, and lanes 2, 5, 7, and 10 were blank.