| Target Gene | Alternative Splicing Event Regulated | Functional Consequence of ESRP1 Regulation | Biological Context | Citation |
|---|---|---|---|---|
| **FGFR2** | Controls mutually exclusive choice of **exon IIIb (epithelial)** versus **exon IIIc (mesenchymal)**; ESRP1 promotes IIIb and represses IIIc by binding intronic regulatory elements including ISE/ISS-3 | Switches receptor ligand specificity: FGFR2-IIIb binds epithelial ligands such as **FGF1, FGF3, FGF7, FGF10, FGF22**, whereas FGFR2-IIIc recognizes **FGF1, FGF2, FGF4, FGF6, FGF9, FGF16, FGF20**; thereby helps maintain epithelial signaling identity and epithelial–mesenchymal state | Canonical ESRP1 target; epithelial cell identity, EMT/MET regulation, developmental epithelial–mesenchymal signaling crosstalk | (pqac-00000000, pqac-00000002, pqac-00000005, pqac-00000011) |
| **CD44** | Promotes inclusion of **variable exons** (CD44v isoforms) and prevents switch to **CD44s** during EMT by binding intronic regions flanking variable exons | Maintains epithelial-associated CD44 isoform profile; blocking ESRP1 expression favors CD44s, which is linked to EMT progression, increased motility, and mesenchymal conversion | EMT regulation and cancer-related epithelial plasticity | (pqac-00000010, pqac-00000000, pqac-00000009) |
| **CTNND1 (p120-catenin)** | ESRP1 regulates alternative splicing of **CTNND1** isoforms; exact exon details not specified in retrieved contexts, but CTNND1 is a validated direct ESRP program target | Supports epithelial cell functions related to **adherens junctions** and cell–cell adhesion; loss of ESRP activity shifts CTNND1 isoform usage and contributes to mesenchymal phenotypes; ESRP1 also has splicing-independent effects on CTNND1 protein abundance | Epithelial junction organization and EMT-associated remodeling | (pqac-00000000, pqac-00000004, pqac-00000009, pqac-00000011) |
| **ENAH (hMena)** | ESRP1 regulates **ENAH/hMena** alternative splicing; precise exon numbers not specified in retrieved contexts, but ENAH is a recurrent ESRP-regulated epithelial target | Promotes epithelial isoforms associated with reduced invasive/migratory behavior; ESRP loss shifts toward mesenchymal splicing patterns that favor altered actin dynamics and motility | Cytoskeletal organization, epithelial morphology, EMT | (pqac-00000000, pqac-00000005, pqac-00000009) |
| **DOCK1 / circDOCK1(2–27)** | ESRP1 promotes back-splicing/biogenesis of **circDOCK1(2–27)** from **exons 2–27** by binding a **GGU-containing repeat region in intron 1** and delaying canonical splicing | Represses cell motility in epithelial cells both by diverting transcripts away from linear **DOCK1 mRNA** production and via direct inhibitory effects of the circRNA on migration | Recent noncanonical ESRP1 function in circRNA biogenesis during EMT-related cell-state regulation | (pqac-00000003) |
| **Multiple ESRP program genes involved in adhesion/polarity/cytoskeleton** | ESRP1 directly binds introns and exons to regulate inclusion or skipping in a **position-dependent** manner: binding **75–250 nt downstream** tends to promote exon inclusion, while binding within the exon or proximal upstream intron tends to promote exon exclusion | Coordinates an epithelial splicing program enriched for genes controlling **cell–cell adhesion, polarity, tight junctions, exocyst/cytoskeletal functions, and migration** | Global epithelial post-transcriptional program; maintenance of epithelial phenotype and suppression of EMT | (pqac-00000004, pqac-00000005, pqac-00000007) |
| **Genes in FGFR/epithelial developmental pathways** | Broad ESRP-dependent epithelial splicing program affecting **134 genes** in early microarray studies and **281 cassette exons** in later RNA-seq/overexpression studies | Produces functionally coherent epithelial isoform networks required for tissue morphogenesis, barrier formation, and epithelial specialization | Mammalian development, epidermal homeostasis, craniofacial and limb development | (pqac-00000009, pqac-00000001, pqac-00000007) |


*Table: This table summarizes well-characterized ESRP1 RNA targets and the functional consequences of their splicing regulation. It is useful for annotating the ghost shark ESRP1 ortholog because it links conserved RNA-binding/splicing activity to concrete epithelial biological outcomes.*