library_construction_protocol: Tumors were excised on day 15 post-transplant, digested with Liberase TL, shredded with Miltenyi C-tubes, ground through a 100um strainer, red blood cells lysed with eBioscience RBC lysis buffer, and then strained through a 70um strainer. Cells were counted and then dead cells were excluded by Miltenyi Dead Cell Exclusion Kit, counted, and submitted for single-cell RNAseq capture. Single-cell RNA libraries were prepared for sequencing using standard 10X Genomics protocols. Single cells were captured and barcoded using the Chromium System with the v3 single cell-reagent kit (10x Genomics). Raw paired-end fastq outputs were concatenated into a single R1 and R2 fastq file for each sample.