22. A diverse set of proteins with conserved RNA-binding domains associate with pre-mRNAs to assist RNA processing. Which is incorrect? (A) RRM (or RBD), KH motif and RGG box are conserved RNA-binding motifs. (B) Pre-mRNAs are associated with hnRNP proteins, contributing to splicing, polyadenylation and expott. (C) To identify hnRNP proteins, first high-dose UV irradiation causes covalent cross-links to form between RNA bases and associated protein, and are recovered by oligo-dT chromatography. (D) The specific monoclonal antibodies of idcntified hnRNP proteins are used to immunoprecipitate the hnRNP proteins complex. (E) All hnRNP proteins shuttle between the nucleus and the cytoplasm for RNA processing.