Animal-free Recombinant Human Cystatin C (Cys-C) is expressed in human 293 cells as a monomer with an apparent molecular mass of 12 to 13 kDa. Native Cys-C in human urine is found in two different forms: one with pI 9.2 and the other with pI 7.8 by elimination of small basic peptides or amino acids from the N-terminal end of protein. Cystatin C has been studied for its role in predicting newonset or deteriorating cardiovascular disease. This cytokine is produced in a serum-free, chemically defined media.