APC and cancer: The functional and potentially pro-tumorigenic consequences of the 3′ UTR lengthening associated with APC loss-of-function mutations or reduced expression remains unclear—in particular, it is unknown which specific 3′ UTR lengthening events are relevant to cancer progression—but this important question could be experimentally answered by functionally interrogating poly(A) site selection in a multiplexed fashion in relevant biological models [17].