FLT1 and breast carcinoma: Furthermore, TAM recruited to the lung, which promotes tumor cell seeding and growth by uniquely expressing FMS-like tyrosine kinase 1 (Flt1, also known as VEGFR1), labels a subset of macrophages in human breast cancers that are significantly enriched in metastatic sites, according to studies using the murine TNBC cell line E0771 [117].