Patients were classified as JAK2 “low” or JAK2 “high” according to their JAK2 mRNA expression level (Fig. S6A) and their enrichment for three previously reported gene signatures: JAK2 direct targets established from JAK2 shRNA knock-down in the HEL cell line32 and JAK2V617F homozygous or heterozygous mutants established in MPN primary patient samples32 as evaluated by single sample Gene Set Enrichment Analysis (ssGSEA) (Fig. S6B). Here, JAK2 is linked to myeloproliferative neoplasm.