Cleavage And Polyadenylation Specific Factor 4 (CPSF4) is a member of the CPSF4/YTH1 family. CPSF4 complex plays a vital role in pre-mRNA 3’-end formation, distinguishing the AAUAAA signal sequence and interacting with poly(A) polymerase and further factors to bring about cleavage and poly(A) additive. CPSF4 binds RNA polymers with a preference for poly(U).