Signaling analyses in the CD34⁺ and CD34⁻ compartment of MPN patients based on mutant JAK2 status. (A) Bar charts of phospho-ERK and phospho-STAT5 staining in CD34⁺ comparing control and MPN patients are shown. No significant differences in signaling are demonstrated between JAK2 wild-type MPN patients and those with mutant JAK2. (B) Signaling patterns were analyzed by mutant JAK2 status in CD34⁻ cells. Bar graphs of ERK and STAT3 signaling are shown. A significant difference was demonstrated in both pathways by JAK2 genotype. (C) A correlation graph comparing the relationship of the JAK2 V617F mutant allele burden in Lin⁻/CD34⁺/CD38⁻ HSCs with the phopho-STAT5 and ERK levels within is shown. The correlation is poor, suggesting that factors other than the JAK2 V617F mutant burden contribute to the signaling demonstrated in MPN patients.