Figure 4.

VEGFR-1 knockdown inhibits tumor angiogenesis and tumor VEGF and MMP9 levels. (A) Representative pictures of immunohistochemical staining of control and VEGFR-1 knockdown tumor sections with antibody against CD31, a marker of blood microvessel. (B) The blood microvessel density was decreased in VEGFR-1 knockdown tumors compared with control tumors. *p < 0.05 vs. control. (C and D) VEGF ELISA analysis of human (C) and mouse (D) VEGF expression in control and VEGFR-1 knockdown tumors. *p = 0.7 vs. their control. **p < 0.01 vs. their control. (E) Representative picture of MMP9 gelatin zymography of control human and mice MMP9 and MMP9 from VEGFR-1 knockdown and control tumors. Human MMP9 was undetectable in both control and VEGFR-1 knockdown tumors. The level of mice MMP9 was decreased in VEGFR-1 knockdown tumors compared with control tumors [*p < 0.05 vs. control, (F)].