Scientists reported new evidence Wednesday that supports a provocative theory about cancer.
Three separate teams of scientists said they had, for the first time, shown that so-called cancer stem cells can be found naturally in brain tumors and early forms of skin and colon cancer.
Evidence has been mounting in recent years for the existence of these cells, which would be especially insidious. They are believed to resist standard chemotherapy and radiation and fuel the growth of tumors and relapses.
The Internet is slowly becoming a less anonymous place. YouTube has a new policy encouraging commenters to use their real names, and many news sites have switched to a login system run by Facebook.
News sites that still allow anonymous comments are finding there are legal risks. The Spokesman-Review newspaper in Spokane, Wash., has spent the last few months trying to protect the identity of a reader who saw a photo of a Republican Party official in Idaho named Tina Jacobson, and then posted a disparaging comment.