Animal-free Recombinant Human TPO is expressed from human 293 cells as a monomeric glycoprotein with an apparent molecular mass of 80 to 85 kDa. This cytokine is produced in a serum-free, chemically defined media. Production in human 293 cells offers authentic glycosylation, contributing to stability in cell growth media and other applications. C- terminal domain glycosylation is thought to be important for the secretion of TPO from cells and for survival of TPO in the circulation.