3'-untranslated regions of various mRNAs have been shown to contain sequence 
motifs which control mRNA stability, translatability, and efficiency of 
translation as well as intracellular localization. We aimed to identify protein 
binding regions of the long and highly conserved 3'UTR of the mRNA coding for 
neurofibromin, a well-known tumor suppressor protein, whose genetic deficiency 
causes the autosomal dominant disease neurofibromatosis type 1 (NF1). We 
discovered five RNA fragments that were able to undergo specific binding to 
proteins from cell lysates (NF1-PBRs, NF1-protein-binding regions). Additionally 
we identified the Elav-like protein HuR binding to NF1-PBR1. HuR interacts with 
AU-rich elements in the 3'UTR of many protooncogenes, cytokines, and 
transcription factors, thereby regulating the expression of these mRNAs on the 
posttranscriptional level. Transfection assays with a CAT reporter construct 
revealed reduced expression of the reporter, suggesting that HuR may be involved 
in the fine-tuning of the expression of the NF1 gene.