CCR4 and prostate cancer: The cytokine CCL2 not only promotes self-renewal by binding to C-C motif chemokine receptor 4 (CCR4) on prostate cancer cells but also recruits tumor-associated macrophages and Tregs in cancer metastasis sites by paracrine, thus creating a profound immunosuppression and angiogenesis microenvironment, confirming once again the importance of CBX7 in tumor immunity (Josefowicz et al., 2012; Su et al., 2019).