But the activated ras pathway (Ras→ Mek → Erk) does not merely cause accelerated cell division; the pathway also intersects with other pathways to enable several other “behaviors” of cancer cells. At Children’s Hospital in Boston in the 1990s, the surgeon-scientist Judah Folkman demonstrated that certain activated signaling pathways within cancer cells, ras among them, could also induce neighboring blood vessels to grow. A tumor could thus “acquire” its own blood supply by insidiously inciting a network of blood vessels around itself and then growing, in grapelike clusters, around those
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