CCR6 and breast cancer: Studies have also shown that, after activation by CXCL12, breast cancer cells secrete another chemokine CCL20 that activates CCR6 expressed by tumor cells and facilitates their proliferation [321], while, in Hodgkin lymphoma, CAFs from tumor-involved lymph nodes cocultured with Reed-Sternberg cells produce CCL5, which activates CCR5 on tumor cells to stimulate tumor growth [205].