DRS-1 gene expression in hematopoietic cells. (A) Total RNA (20 μg) from each cell line was subjected to ribonuclease protection assay using biotin-labeled DRS-1 RNA probe and GAPDH RNA probe. The protected GAPDH probe and DRS-1 probe were visualized at 310 bp and 235 bp, respectively. (B) The same amounts of cDNA derived from each cell line or CD34⁺ cells were used to amplify DRS-1 or GAPDH, respectively. Relative expression levels of DRS-1 to GAPDH were determined as DRS-1/GAPDH. The levels for CD34⁺, PBMCs, and LCLs represent mean + SD of 3, 6, and 7 healthy individuals, respectively.