EBV-CTLs transduced with CN mutants show a selective advantage when cultured in FK506/CsA. Retrovirally transduced EBV-CTL lines were grown in the presence or absence of CN inhibitors for 3 weeks, and the percentage of cells expressing GFP were assessed by flow cytometry at various time points. Mean GFP expression ± SEM are shown (n = 5). (A) Expression of GFP when cultured without CN inhibitors. The proportion of transduced CTLs remains stable in all but the CNa22 culture, where the number of transduced cells drops. (B) Addition of 10 ng/mL FK506 to cultures results in an enrichment of GFP expressing CTLs in those that are resistant to FK506 (CNa12 and CNb30). (C) Addition of 200 ng/mL CsA to CTL cultures results in a rise in GFP-expressing CTLs in CsA-resistant cultures (CNa22 and CNb30).