SDS-PAGE analysis of tD15 purification, performed on a 12.5% gel. Lane 1, prestained protein molecular weight markers; lane 2, purified GST; lane 3, GST-tD15 fusion protein eluted from glutathione-Sepharose 4B column; lane 4, GST-tD15 fusion protein cleaved by thrombin; lane 5, tD15 recovered in the run-through fraction from the glutathione-Sepharose 4B column; lane 6, GST eluted from the glutathione Sepharose 4B column.