Recent observations raise possibility for constitutively active, mutated JAK2 to modulate expression of RAS genes in CMPD. We analyzed the expression of AGT, renin, AT2R1 and ACE genes in normal and bone marrows of PV and ET patients with the respect to the presence of V617F JAK2 mutation. PV and ET had different expression patterns of major RAS components compared to normal BM which was primarily associated with the JAK2V617F mutation and less with PV or ET disease phenotype. However, AT2R1 was exclusively markedly upregulated only in PV, while ET showed moderate expression irrespective of the JAK2 mutational status.