rtTA-7-ERp72 cells, either uninduced or induced to overexpress ERp72 by 96 h of doxycycline treatment (Dox), were pulse-labeled with 35S-labeled amino acids for 30 min in the presence of dithiothreitol (DTT) at the concentrations shown. At the end of the labeling period, in situ reduction was terminated by the addition of N-ethylmalemide, and the cells were lysed, immunoprecipitated for Tg, and analyzed by SDS-PAGE and phosphorimaging.