Quantitative platelet Mpl protein expression in the MPDs stratified by disease and neutrophil JAK2 V617F status. Platelet Mpl protein expression and neutrophil JAK2 V617F allele percentages were determined in 70 PV, 69 ET, and 13 IMF patients. Patients in each disease category are stratified by neutrophil JAK2 V617F allele percentage of more than 95%, between 5% to 95%, and less than 5%. Boxes indicate the quartiles of the distribution; medians are indicated by black lines. Linear regression analysis of neutrophil JAK2 V617F allele percentage and platelet Mpl expression in 101 PV, ET, and IMF patients was significant (P < .001) with a correlation coefficient of –0.390 (inset).