PCR analysis of vector DNA in T cells derived from transduced CD34⁺ progenitor cells. Rhesus CD34⁺ cells were transduced with either the LNL6 or p9456t retroviral vectors and then cultured on thymic stroma to support T-cell differentiation. T cells derived from transduced progenitor cells were expanded in the presence of G418 and then 100 ng of DNA was analyzed for the presence of vector DNA by PCR using primers specific for the neo gene. The neo titration samples consisted of the indicated percentage of CEMx174 cells stably transduced with the retroviral vector LN diluted in rhesus genomic DNA.