Figure 2. Schematic representation of VEGF-A, -C, and -D mRNAs. (A) VEGF-A mRNA is characterized by a long 5′UTR (1038 nt) containing two internal ribosome entry sites (IRESs) (A and B). The VEGF-A gene encodes multiple isoforms generated by mRNA splicing of four constitutive and four alternative exons. (B) VEGF-C mRNA possesses a GC-rich 5′UTR containing one IRES. The secondary structure of VEGF-C IRES has been determined by shape analysis and contains 2 motifs (indicated by boxes) showing a similar reactivity pattern between human and mouse mRNA. (C) Similar to VEGF-C, the VEGF-D mRNA is generated from 7 exons.