library_construction_protocol: Subcutaneous B16 tumours were implanted on the back mice. On day 19 after tumours were injected, tumors were collected, weighed and chpped before chemical and mechanical digestions with Tumour Dissociation Kit II (Myltenyi) and gentleMACS DIssociator (Myltenyi) using the m-TDK-1 program. Immune cells were isolated by density centrifugation with Lympholyte (Cederlane Labs) followed by positive selection for CD8a+ cells (Myltenyi). CD8+ cells were pooled into samples from 5-11 tumours, depending on cell counte recovered. Live cells were sorted into Tim3+ and Slamf6+ populations with two pooled samples per treatment condition. Libraries were constructed by incubating 15,000 Slamf6+ or 31,000 Tim3+ cells with transposition mix, which contains 2x TD Buffer, Tn5 Transposase and 1% digitonin, at 1,000 cells/uL for 30 minutes at 37 C with agitation at 1000 RPM. DNA was purified using Qiagen MinElute Reaction Kit. During the library construction Ilumina R2 primer sequence, paired-end constructs with P5 and P7 sequences and a sample index were added.