In the tumor microenvironment, S1P exhibits multiple functions: (a) it increases the survival of macrophages; (b) it serves as the “come-and-get-me” signal of dead cells, attracting and enhancing macrophage migration by combining with S1PR1; (c) it stimulates the polarization of TAM/M2 macrophages by activating S1PR1/2/4 [9–11]. The gene discussed is S1PR1; the disease is neoplasm.