TUT1 and neoplasm: However, another canonical mammalian poly(A) polymerase γ (PAPOLG) has been found in the nuclei of many tumor cells and cell lines21 and was the only poly(A) polymerase detected in a proteomic study of polyadenylation complexes.22 In addition, the noncanonical poly(A) polymerase TUT1 (Star-PAP, PAPD2) has been shown to mediate the nuclear polyadenylation of specific mRNAs.23–28