CRF1 splicing variants differ in the number of exons (filed squares). Removed exons were shown as a line and exons with frame-shift as empty squares. Number of the exon (1 to 14) is indicated on the top. Names of CRF1 isoforms are indicated on the left. Isoforms α, β, c, d, e, f, g and h were detected in humans, mouse or hamster. CRF1e2 and CRF1h2 are theoretical alternative transcript from the same mRNA of CRF1e and h, respectively. Isoforms j, k, m and n were found only in hamster and isoform oCRF1var in sheep. Greek letters and doted boxes indicate transmembrane fragments I to VII. Modified after (Slominski et al., 2006b).