CBA analysis showed an important decrease of phospho-STAT1 in PV samples patients (ratio of pSTAT1 in PV without treatment: 29.2; ratio of pSTAT1 in PV samples with KNK437, 50 μM: 21.55), however, we found no significant differences in phospho-STAT1 with and without KNK437 treatment in ET patients. The gene discussed is STAT1; the disease is acquired polycythemia vera.