Pre-mRNA binding protein in vivo, binds avidly to poly(G) and poly(U) RNA homopolymers in vitro. Involved in splicing. Acts as a receptor for carcinoembryonic antigen in Kupffer cells, may initiate a series of signaling events leading to tyrosine phosphorylation of proteins and induction of IL-1 alpha, IL-6, IL-10 and tumor necrosis factor alpha cytokines. Identified in the spliceosome C complex (PubMed:11991638). Interacts with PPIA/CYPA (PubMed:25678563). Experimental confirmation may be lacking for some isoforms. Sumoylated.