demonstrated by immunoprecipitation assay and deacetylation assay that SIRT7 not only improves the stability of USP39 protein by deacetylating the K428 site on the USP39 structure, but also participates in the activation of the SIRT7/USP39/FOXM1 positive feedback loop, providing a new idea for targeted treatment of CSCC (45). This evidence concerns the gene USP39 and skin squamous cell carcinoma.