C-C motif chemokine 2 (CCL2) appeared to be secreted from RB1-deficient breast cancer cells, thereby such tumor cells recruit immunosuppressive cells including myeloid-derived suppressive cells (MDSC), regulatory T cells (Treg) or macrophages, allowing malignant progression following RB1 inactivation. The gene discussed is CCL2; the disease is breast carcinoma.