FLT1 and neoplasm: Consistent with the effect of antibody blockade of VEGFR1, we detected a significant decrease in the number of CD11b+ cells but not VEGFR1+ cells in the peri-tumor areas in LLC1 lung metastases from (non-irradiated) flt-1TK–/–/C57BL and C57BL mice (Figure 7C,F,G).