News Life Running a cancer roadblock Research details how breast tumors thwart a protective piece of RNA By Tina Hesman Saey February 3, 2011 at 4:53 pm - More than 2 years ago Share this:Share Share via email (Opens in new window) Email Share on Facebook (Opens in new window) Facebook Share on Reddit (Opens in new window) Reddit Share on X (Opens in new window) X Print (Opens in new window) Print A small piece of RNA forms a big roadblock for breast cancer cells trying to spread away from the original tumor. This scrap of genetic material, a microRNA dubbed miR-335, stops tumor cells from making key proteins that allow the cells to move around the body.