CD4 and neoplasm: Moreover, CCR2 was expressed in multiple immunosuppressive cells, such as CD4+FOXP3+ CCR2+ Treg cells [49], CCR2-expressing myeloid-derived suppressor cells (MDSCs) and tumor-associated macrophages (TAMs), which were recruited to the tumor site through the expression of CCR2 and play a critical role in tumor escape [50, 51].