Mesothelin Is Shed from Tumor Cells

A. SMPs in culture supernatant of A431/K5 cells were purified and analyzed with or without PNGase F digestion by SDS-PAGE. Recombinant bacterial mesothelin proteins (rMSLN) were used as a control. Deglyco, N-linked deglycosylation. B. SMPs were analyzed by mass spectrometry. Underline, the identified peptide sequences were aligned with membrane-bound mesothelin (MSLN). Box, NH₂-terminal sequence. *, predicted glycosyl-phosphatidylinositol cleavage site. C. The SMP was recognized by an anti-MSLN antibody but not by an anti-cross-reacting determinant (Anti-CRD) antibody by Western blot. sVSG, soluble form of variant surface glycoprotein; mf-VSG, the membrane form of VSG.