Our previous work showed that Tregs form a functionally important T-cell subgroup in cSCCs which suppress antitumor immunity and associate with development of metastasis.16 It has been shown that CD103 can be expressed by Tregs in murine cancers,41 but only 1.1% of tumor-infiltrating CD4+FOXP3+ Tregs were CD69+CD103+ in our study (figure 4C), indicating that the Tregs and CD103+ TRMs in cSCCs are separate cell populations. This evidence concerns the gene CD4 and cancer.