RNA-binding protein that plays a role in the regulation of alternative splicing and influences mRNA splice site selection and exon inclusion. May play a role as a negative regulator of cell growth. Inhibits cell proliferation. Involved in splice site selection of vascular endothelial growth factor. Induces an increased concentration-dependent incorporation of exon in CD44 pre-mRNA by direct binding to purine-rich exonic enhancer. RNA-binding abilities are down-regulated by tyrosine kinase PTK6. Involved in post-transcriptional regulation of HIV-1 gene expression. Binds preferentially to the 5'-[AU]UAAA-3' motif in vitro.