FLT1 and neoplasm: Cytochrome P450 (CYP) 4A in tumor-associated macrophages can promote the formation of a pre-metastatic niche (evidenced by the recruitment of VEGFR1+ myeloid cells) and further affect metastasis, and the combined blocking of TGF-β, VEGF, and SDF-1 can suppress VEGFR1+ myeloid cell migration and fibroblast activation induced by CYP4A (Zhao et al. 2016; Chen et al. 2017).