NOS2 and atrial fibrillation: As shown in Figure 6A, the AF from ovarian patients predominantly upregulated the expression of ARG1 and iNOS in CD14+HLA-DR–/low MDSC with slight increased expression of S100A8 and S100A9; we further confirmed that both ARG1 and iNOS expression were dependent on the STAT3 activation since STAT3 inhibition by Stattic abrogated their upregulation in AF-induced CD14+HLA-DR–/low MDSC (Figure 6B).