CD8A and melanoma: In a study of the underlying roles and mechanisms of miR-155 in melanoma progression, miR-155 expression was found to be upregulated in effector CD8+ T cells depending on the strength of TCR stimulation and differentiation, and miR-155 knockout promoted tumor growth by enhancing the SOCS-1/STAT5 signaling pathway, thereby impairing cytokine production and resulting in CD8+ T cell exhaustion (63).