library_construction_protocol: Three mice (a total of six tumors) were performed on each cell line. Based on the visual observation of subcutaneous tumor growths, the mice injected with the same cell lines were sacrificed on the same days after 3-4 weeks. (A431: 3.5 weeks, Cal27: 4.5 weeks) The tumors were surgically harvested, minced, and homogenized in an MP Biomedical lysing matrix A tube. Genomic DNA was isolated using QIAGEN DNeasy Blood and Tissue Kit Sequencing library was made as described in (Mathiowetz et al. 2023, PMID: 37000620) with an adjustment of using <10g of gDNA in PCR1 reaction and a pair of primers matching with our sequences and manually determining PCR2 cycles based on a trial run to prevent overamplification.