CCL22 and neoplasm: CTLs and suppressive cells are attracted to tumor tissues by different chemokines: Th1/NKs/CTLs-attracting chemokines include CCL5 (regulated upon activation, normal T cell expressed, and secreted; RANTES), CXCL9 (monokine induced by gamma interferon; MIG) and CXCL10 (Interferon gamma-induced protein 10; IP10), while neutrophils, MDSCs, and Tregs are attracted by, respectively, CXCL8 (interleukin 8; IL-8), CXCL12 (stromal-derived factor-1; SDF1) and CCL22 (myeloid-derived chemokine; MDC) [29,30,31,32].