mRNA splicing factor that regulates the formation of epithelial cell-specific isoforms. Specifically regulates the expression of FGFR2-IIIb, an epithelial cell-specific isoform of FGFR2. Also regulates the splicing of CD44, CTNND1, ENAH, 3 transcripts that undergo changes in splicing during the epithelial-to-mesenchymal transition (EMT). Acts by directly binding specific sequences in mRNAs. Binds the GU-rich sequence motifs in the ISE/ISS-3, a cis-element regulatory region present in the mRNA of FGFR2 (By similarity). Regulates splicing and expression of genes involved in inner ear development, auditory hair cell differentiation, and cell fate specification in the cochlear epithelium (PubMed:29107558). Epithelial cell-specific. Epithelial-specific expression in diverse tissues and organs with particularly notable levels of expression in skin and gastrointestinal epithelia. It is broadly expressed throughout the epithelium of the otic vesicle at embryonic day 10.5 dpc, but it is absent from the surrounding mesenchyme. High expression is detected in sensory and non-sensory epithelial progenitors during cochlear and vestibular morphogenesis, although the level is weaker at later stages of inner ear development. Homozygous knockout mice die soon after birth due to complications from cleft-lip and palate defects. Knockout embryos show alterations in inner ear morphogenesis and auditory hair cell differentiation. Belongs to the ESRP family.