Johns Hopkins Medicine May 8 2026 Since a landmark 2009 study, researchers have known that a common gut bacterium, Bacteroides fragilis , drives colon tumor formation, potentially leading to colorectal cancer, by secreting a toxin that damages the lining of the colon. But until now, the exact mechanism the toxin uses to latch onto those cells remained a mystery.  A multi-institutional team led by researchers at the Johns Hopkins Kimmel Cancer Center Bloomberg~Kimmel Institute for Cancer