All procedures have been described before (23 (link)). All antibody labeling was performed on ice for 20 min, followed by washing and centrifugation. Cells were stained with directly conjugated antibodies to mouse CD45 (30-F11-APC, eBioscience), mouse CD31 (390-APC, BioLegend), Ter119 (TER-119-APC, eBioscience), and human HLA-A, B, C (G46-2.6-BV421, BD Biosciences) to select live human melanoma cells and exclude endothelial and hematopoietic cells. Cells were examined on an LSRFortessa cell analyzer (BD Biosciences) or sorted on a FACSAria cell sorter (Becton Dickinson). SETDB1 or EZH2 knockdown cells were sorted as DsRed and green fluorescent protein (GFP) double-positive cells.