<Journal class="Journal" value="Proceedings of the National Academy of Sciences of the United States of America" /> <Page class="#txt" value="6117"> <Page-2 class="#txt" value="21" /> </Page> <Volume class="#txt" value="88" /> <Year class="Year" value="1991" /> </Reference> <Author class="Author" value="Kreienkamp HJ" /> <Author class="Author" value="Weise C" /> <Author class="Author" value="Raba R" /> <Author class="Author" value="Aaviksaar A" /> <Author class="Author" value="Hucho F" /> <Medline class="Medline" value="2068091" /> <Abstract class="LongText" value="Kreienkamp_1991_Proc.Natl.Acad.Sci.U.S.A_88