Distinct signatures of CD8+ T cells, such as TCF-1+ and CX3CR1+, are correlated with effective anti-tumor immune responses.98,99,238 Similarly, specific features of Treg cells, like CCR8+ Treg cells, may be linked to tumor advancement400,401 or response to PD-1 immunotherapy (IFNγ+ Treg cells).402 The heterogeneous and malleable characteristics of TAMs and TANs result in distinct pro-tumor (M1 TAMs and N2 TANs) and anti-tumor (M2 TAMs and N1 TANs) phenotypes. The gene discussed is CX3CR1; the disease is neoplasm.