STAT3 and renal cell carcinoma: Primary CD15+ myeloid cells, including PMN-MDSCs, were enriched from treatment-refractory RCC patients’ PBMCs and incubated with CpG-STAT3ASO to knockdown STAT3 or with non-targeting but immunostimulatory CpG-scrON oligonucleotide (Figures 4A, B).