NKG2DL mRNA expression by PBMCs of leukemia patients. RNA from PBMCs of 2 healthy donors (HD1 and HD2) and 4 leukemia patients (UPN 1, UPN 4, UPN 5, UPN 20) was extracted and reverse transcribed. Relative copy numbers of NKG2DL were determined by real-time PCR using NKG2DL-specific primer pairs and normalized with 18S rRNA expression. Relative increase in relative copy numbers was calculated as outlined in “Patients, materials, and methods.” Relative copy numbers of HD1 were defined as 1. Error bars indicate the error propagation taking into account the SDs of the means of the 4 duplicates used for calculation of the relative increase in relative copy numbers.