Given a passage, construct a question on the basis of the information present in the passage. Construct the question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) it answer uses text phrases from the passage. Avoid creating questions that (i) can't be answered correctly without actually understanding the passage and (ii) uses the same words or phrases given in the passage.

[Q]: The role of Kdr (VEGFR-2/Flk-1) in vascular formation has been well described, but the role of Flt1 (VEGFR-1) is not well studied and is generally considered as a decoy receptor for trapping VEGF.', 'The effects of VEGFR1/2 kinase inhibitor (VRI) and calycosin on Flt1 tyrosine kinase (TK) activity were evaluated by molecular docking, enzymatic inhibition assay, protein co-immunoprecipitation and siRNA gene knock-down analysis in HUVECs. Toxicities of the chemicals were examined using HUVECs viability. Their effects on angiogenesis and vessel formation were furthered studied in HUVECs in vitro and Tg(fli-1:EGFP) zebrafish in vivo. The gene and protein expression of VEGF and VEGF receptors were investigated by quantitative RT-PCR and Western blot.', 'VRI strongly inhibited physiological functions of both VEGF receptors and suppressed endothelial cell survival. This resulted in blood vessel loss in zebrafish embryos. Interestingly, calycosin co-treatment impeded VRI-induced blood vessel loss. Docking and kinase inhibition assay revealed that calycosin competed with VRI for the tyrosine kinase domain of Flt1 without affecting ATP binding. On the contrary, calycosin did not affect the interaction between VRI and Kdr-TK. Consistent with these results, calycosin counteracted the inhibition of Flt1-TK and PI3K phosphorylation induced by VRI in HUVECs. Further studies in vitro and in vivo showed that the minimizing effect of calycosin on VRI-mediated endothelial cytotoxicity was blocked by wortmannin (a PI3K inhibitor). The impeding effect of calycosin on VRI-induced blood vessel loss was absent in zebrafish embryos injected with Flt1 MO.
[A]: Is basal Flt1 tyrosine kinase activity a positive regulator of endothelial survival and vascularization during zebrafish embryogenesis?

[Q]: To describe the novel use of a chorioretinal biopsy technique to confirm the microbiological diagnosis of endogenous Escherichia coli (E. coli) endophthalmitis, when other investigations have been proven nondiagnostic.', 'Case report of an 82-year-old white man with endogenous endophthalmitis without a clearly identifiable source of infection.', 'After systemic cultures and multiple aqueous and vitreous samples were unable to identify a causative organism, chorioretinal biopsy of a subretinal abscess was used to confirm the microbiological diagnosis. This ensured appropriate ophthalmic and systemic treatment of infection.
[A]: Do cHORIORETINAL BIOPSY FOR THE DIAGNOSIS OF ENDOGENOUS ENDOPHTHALMITIS DUE TO ESCHERICHIA COLI?

[Q]: XIAP-associated factor 1 (XAF1) is a tumor suppressor gene, but its role in angiogenesis is unknown. We investigated whether XAF1 has any antiangiogenesis effect.', 'MS1 (a mouse endothelial cell line) was infected with an adenoviral vector ZD55-XAF1. Controls were uninfected or infected with ZD55-EGFP. Wound healing assay and tube formation assay were used to assess angiogenesis. Cell proliferation was detected by WST-1 assay, and apoptosis was detected by TUNEL and APOPercentagetrade mark assays.', 'ZD55-XAF1 significantly upregulated XAF1, which was associated with decreased cell proliferation, migration and tube formation of MS1 cells. Ectopic overexpression of XAF1 induced apoptosis in MS1 and also sensitized cells to 5-fluorouracil-induced apoptosis. A significant decrease in the expression of Tie-1, Ang-1, Ang-2 and c-Myc was observed.
[A]:
Does xIAP-associated factor 1 ( XAF1 ) suppress angiogenesis in mouse endothelial cells?