library_construction_protocol: For whole A375 tumor sample, human tumor dissociation kit (Miltenyi Biotec, 130-095-929) was used to obtain the single suspension. For sorted A375 tumor cell sample, A375-GFP tumor model was established and sorted based on the human HLA-A,B,C antibody and GFP signal. The result signle cells were barcode labelled and library constructed by Single Cell 3' Reagent Kits v3 (10× genomics, Genergy BIO-technology, Shanghai, China). The constructed library was sequenced on an Illumina NovaSeq 6000 System.