Our data showed a coordinated downregulation of RORγt with decreased Th17 cell percentage and IL-17 production in a dose-dependent manner in CD4+ T cells of PV patients in the presence of DAPT, which provides further evidence that RORγt can regulate Th17 cells directly, and the inhibition of the Notch1 signaling can disrupt Th17 cell differentiation and function through the downregulation of RORγt expression in PV. Here, NOTCH1 is linked to acquired polycythemia vera.