The RNA-binding protein HuR binds at 3' untranslated regions (UTRs) of target 
transcripts, thereby protecting them against degradation. We show that HuR 
directly interacts with cellular retinoic acid-binding protein 2 (CRABP2), a 
protein known to transport RA from the cytosol to the nuclear retinoic acid 
receptor (RAR). Association with CRABP2 dramatically increases the affinity of 
HuR toward target mRNAs and enhances the stability of such transcripts, 
including that of Apaf-1, the major protein in the apoptosome. We show further 
that its cooperation with HuR contributes to the ability of CRABP2 to suppress 
carcinoma cell proliferation. The data show that CRABP2 displays antioncogenic 
activities both by cooperating with RAR and by stabilizing antiproliferative HuR 
target transcripts. The observation that CRABP2 controls mRNA stabilization by 
HuR reveals that in parallel to participating in transcriptional regulation, the 
protein is closely involved in posttranscriptional regulation of gene 
expression.