Sensitivity and specificity of JAK2 mutation–specific real-time PCR. JAK2-V617F mutation–positive UKE-1 cells were diluted at different amounts into PBMNCs obtained from healthy donors. UKE-1 cells were regularly detectable at dilutions of at least 1 in 10 000 PBMNCs (A). The strongly linear standard curve (B) and the absence of positive signals when analyzing healthy donor–derived cells (n = 60, not shown) indicate high specificity of the described real-time PCR.