Naked mole rats don't get cancer and now we finally know why—a new study shows that this tiny rodent's cells are surrounded by antitumor goo. Made of long sugar chains called hyaluronan, this goo also makes skin elastic, lubricates joints, and promotes healing. While other animals and people likewise have hyaluronan around their cells, the type in naked mole rats is bigger and builds up to higher levels. The researcher found that after the goo was removed, naked mole rat cells that were grown in the lab could be made malignant and formed tumors when placed in mice. Next, the researchers will test whether the hyaluronan from naked mole rats also prevents cancer in mice. If it does, they'll test this tumor-preventing goo on human cells.