CCL21 and neoplasm: The CXCL12/CXCR4 axis is important for tumor cell survival and metastasis, CAF activation, and recruitment of monocyte-derived cells (Chatterjee et al., 2014) CCL21 signaling; on the other hand, it can recruit lymphocytes, NK cells, and antigen presenting cells with anti-tumor activity (Lin et al., 2014; Figure 1).