What is NCBI Refseq and where do I get it?
NCBI’s Refseq is an attempt at the creation of standard reference sequences for all the various sequences, including mRNAs. These mRNAs can be located within the nt database, available via FTP from NCBI. RefSeq mRNAs have accession numbers that begin with NM_. For more information on RefSeq, see the RefSeq home page.