Regarding the mechanism of MDSC recruitment and activation, in addition to activation of the JAK-STAT signaling pathway by GM-CSF, IL-6, and VEGF, Dickkopf-1 (Dkk1) promotes the accumulation of MDSCs and downregulates β-catenin expression in MDSCs from mice and humans, all of which exert an immunosuppressive effect on tumor progression [97,98]. The gene discussed is VEGFA; the disease is neoplasm.