Isolation of a Tumor Factor Responsible for Angiogenesis by Judah Folkman and others 2026-11-05
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Original byline: Judah Folkman, Ezio Merler, Charles Abernathy and Gretchen Williams. Journal of Experimental Medicine 133(2), 275–288 (1971), DOI 10.1084/jem.133.2.275; PMID 4332371. Printed p. 275 describes new-vessel outgrowth near membrane chambers containing tumor cells in rat dorsal air sacs, motivating a diffusible-factor interpretation; the abstract reports an angiogenic tumor-derived fraction. Publisher PDF: rupress.org/jem/article-pdf/133/2/275/1084025/275.pdf . The historical fraction is not equated with a single modern chemically defined growth factor.
Additional verified locator: printed p. 279, Biological Assay of TAF and Reading the Air Sac Assay; Figures 1–4. The modified rat dorsal air sac assay used a membrane wick over holes in silicone tubing to deliver tumour fractions, read after 48 hours under a stereoscope at 20×, followed by histological sections. Vascular proliferation was graded 0–5+. Figure 2 shows a negative wick control; Figures 3–4 show positive responses. This biological activity scale is not an absolute endothelial cell count. Primary full-text indexed view: pmc.ncbi.nlm.nih.gov/articles/PMC2138906/ .
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