Blood vessel growth factor also does housekeeping.

The growth of new blood vessels, a process known as angiogenesis, is spurred by a molecule called vascular endothelial growth factor (VEGF). Seientists had thought that VEGF's role was mainly to carry messages between cells, but new research shows that VEGF also acts within the cells lining normal blood vessels to keep them alive and functioning correctly. The finding may explain certain vascular side effects of cancer drugs that silence VEGF in order to inhibit blood vessels that feed a growing tumor.

M. Luisa Iruela-Arispe and her colleagues at the University of California, Los Angeles developed a strain of mice that can't produce VEGF. Most of these mice died by early adulthood--about 25 weeks--and had vascular problems, including symptoms similar to those of a heart attack.

Lacking VEGF, the cells lining normal blood vessels died prematurely, the researchers report in the Aug. 24 Cell. But adding VEGF to the cells didn't restore normal function, the team also found.

Although the researchers didn't test the impact of antiangiogenesis drugs in this study, Iruela-Arispe says that "long-term blockage of [VEGF] may have long-term consequences that we did not foresee a few years ago." She's quick to emphasize, however, that these potential side effects don't outweigh the potential importance of anti-angiogenesis drugs in fighting cancer.--S.W.