Claim: The hnRNPs (heterogeneous nuclear ribonucleoproteins) are RNA binding proteins associated with pre-mRNAs in the nucleus, that form complexes with heterogeneous nuclear RNA (hnRNA).
Evidence: However, since most mature RNA is exported from the nucleus relatively quickly, most RBPs in the nucleus exist as complexes of protein and pre-mRNA called heterogeneous ribonucleoprotein particles (hnRNPs).