Predicted amino acid sequences of the three isoforms, L552S, XAGE-1, and XAGE-1b. Earlier reports predicted three potential open reading frames. L552S (160 aa), XAGE-1 (146 aa), and the shortest isoform XAGE-1b (81 aa) are shown here. Two major epitope regions (peptide #4/#5 and peptide #29) and two minor epitopes (peptide #17 and peptide #24) recognized by patient Abs are indicated by dotted lines.