Quantitative RT-PCR analysis for MDR1 gene. Intensity of MDR1 expression is shown as a ratio of the density of the bands for MDR1 and β2m. Lanes 1 through 3, 4 through 9, 10 through 12, and 13 and 14 are NK cells from the normal donors, indolent NK-GLPD, aggressive NK cell tumors, and NK cell lines, respectively. Lanes 4 through 12 correspond to patients 1 through 9 of Table 1, respectively. Lane 13 is the cell line NK92, and lane 14 is the cell line NKL.