These data are consistent with a published genome-wide transcriptome analysis of CD34+ cells from a large number of MPN patients (28), demonstrating that CD34+ cells from JAK2V617F MPNs express a significantly higher level of RAB27B, but not RAB27A, compared with healthy controls (Figure 2E and Supplemental Figure 1A). Here, RAB27B is linked to myeloproliferative neoplasm.