CCR1 and cancer: For example, CCR1 expression in cancer cells is critical for fibroblasts to stimulate breast cancer cell proliferation [53], CCR2 exhibited a pro-tumor effect by stimulating the recruitment of monocytes/macrophages in lymphoma, melanoma, and breast cancer [54,55], and CCR3 was overexpressed in malignant cutaneous tumors, including malignant melanomas [56].