Analysis of TRAIL protein.

(A) Silver staining of SDS-PAGE analysis of purified recombinant TRAIL, performed in reducing and nonreducing conditions. Sizes of the molecular mass markers are indicated in kilodaltons (kd) on the left. Sizes of TRAIL monomers, dimers, and trimers are indicated on the right. The gels shown are representative of 5 purification experiments. (B) Evaluation of the cytotoxic activity of human recombinant TRAIL (1 μg/mL) on erythroleukemic cell lines. Viable cells were counted by trypan blue dye exclusion at 6 and 24 hours after the addition of either TRAIL or His6-tag control peptide in culture. Data are expressed as percentage control (His6-tag peptide-treated) cells and represent the mean ± SD of 5 independent experiments performed in duplicate.