FLT1 and neoplasm: BMDCs mobilized by factors released by the primary tumor and expressing VEGFR1 create a suitable microenvironment for metastatic colonization before CTCs arrive.128 Various specific inhibitors of VEGFR1, including ribozyme,271 mAb,272 peptides,273 and DNAzyme,274 have been found to inhibit tumor metastasis formation.