CD4 and neoplasm: Although our research strongly supports the idea of the predominant expression of CXCR6 on CD8+ T cells and the facilitation of antitumor activity during CXCR6 knockout, without extensive exploration of the implications of CD4+ T cells in the tumor microenvironment, a gap in understanding of the role of CXCR6 in CD4-mediated tumor immunity remains.