1.   Most tumors secrete hormones that stimulate new vessel growth around them, to speed delivery of oxygen-rich blood.

2.   Eventually, they discovered that tumors themselves secrete chemicals that trigger this blood vessel growth, or angiogenesis.

3.   Folkman has shown that primary tumors can secrete antiangiogenic substances that keep secondary cancer growths from spreading.

4.   Indeed, Folkman said in Amsterdam that some breast tumors secrete six different signals to build blood vessels.

5.   It is curious that many tumors should secrete inhibitors as well as inducers of angiogenesis.

6.   It is also effective in blocking a substance some tumors secrete, which signal the body to grow more blood vessels.

7.   Then the researchers found a second protein fragment, secreted by tumors, that also squelches metastases, Folkman said.