Lyophilized powder may be stored at 4 degree C for short-term only. Reconstitute to nominal volume by adding sterile 0.2% sodium chloride and store at -20 degree C. Reconstituted product is stable for 12 months at -20 degree C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.