Proliferation of parental or selected and transduced NK cell lines in short-term cultures. Cells were adjusted to the concentration of 1 × 10⁴ cells/200 μL in wells of a U-bottom microtiter plate and incubated ± IL-2 at various concentrations for 4 days. ³H-TdR incorporation was measured during the last 16 hours of culture. *P < .05 for differences in growth between parental and transduced NK cells.