In PV, SCF did not induce further increase of cKITY703 and cKITY721, both as total and stoichiometry values, while these forms were significantly increased as total levels by SCF in AB and CB (Figures 5A,B, Figures S6A,B, Tables S4–S6), providing further support for the hypothesis that in PV the presence of JAK2V617F prevents GFD to reset cKIT activity. Here, KITLG is linked to acquired polycythemia vera.