CCL1 and skin squamous cell carcinoma: To evaluate the relevance of our observations to clinical prognosis, we analysed public data from The Cancer Genome Atlas (TCGA), which revealed that increased levels of IL-10, Sp1, and CCL1 correlate with poor prognosis in CSCC patients (P = 0.0324, P = 0.0296, and P = 0.0436, respectively) (Fig. 6g–i), further suggesting that IL-10, Sp1, and CCL1 play oncogenic roles in the metastatic progression of CSCC.