However, in most MCC tumors, only a limited number of CD8+ cells penetrate the malignant tumor mass that rather tends to form peripheral clusters together with inflammatory cells, suggesting the setting of abnormal signaling as a consequence of the deregulated expression of numerous chemokines and receptors (e.g., CXCL9-12, CXCR4, and CXCR3) [74]. This evidence concerns the gene CD8A and Merkel cell skin cancer.