HPLC separation and mass spectrometric analysis of I540 and R572 peptides from the cell surface of aAPC/hTERT. (A) Primary structure of EGFP-hTERT is shown. (B) Expression of transduced EGFPTERT (open curve) was analyzed by flow cytometric analysis using the FL1 channel. Untransduced aAPCs were used as a control (filled curve). (C) Cell-surface peptides from aAPC/hTERT were acid stripped and separated by reverse-phase HPLC as described in “Materials and methods.” Peptide fractions were collected, subjected to mass spectral analysis, and fractions corresponding to those of synthetic I540 and R572 peptides were identified.