JAK2 and myeloproliferative disorder: To evaluate whether surface antigens that were up‐ or down‐regulated on MPN NSC (compared to HSC) and/or correlated to a degree with the JAK2V617F allele burden are expressed on MPN cells in a JAK2‐dependent manner, MPN MNC were incubated in various concentrations of fedratinib (1–5 μM) or ruxolitinib (1–10 μM) for 24 h.