CSF2 and neoplasm: Cytokines such as the FMS-like tyrosine kinase 3 ligand (FLT3L) or the granulocyte–macrophage colony-stimulating factor (GM-CSF) are able to recruit and activate DCs in the tumor microenvironment [50,51] and are currently being tested in different clinical trials as mono or combinatorial therapy (Figure 1a and Figure 2) [52].