Dis3l2 is protein that preserves the character of stem cells by degrading specific messages. But how does the enzyme know which messages to destroy? CSHL researchers obtained a molecular photograph (imaged on the left) of the protein in complex with a 'poly-U' chain (in orange) that marks messages for degradation. The poly-U chain is inserted into a funnel-like structure deep within Dis3l2 (see cartoon on the right, poly-U chain again in orange). Inside the funnel, there are more than a dozen contacts that capture the poly-U mark so that the entire message can be destroyed.