A and B Non-reducing and reducing SDS-PAGE gels and densitometry for rHA proteins on days 0 and 28. A. Each rHA (~2.5 μg) was analyzed by SDS-PAGE under non-reducing (N-R) and reducing (Red) conditions on days 0, 7, 14 or 21, and 28. Shown are gels obtained on day 0 (top) and on day 28 (bottom). Densitometry was performed on the non-reducing lanes on the left-hand-side of each gel using the Carestream software program, and the corresponding intensity profiles are shown on the right. B. The intensities of individual bands in the non-reducing SDS-PAGE gel profiles were measured using the Carestream software program. The ratio of intensities for cross-linked bands migrating above the 70 kDa marker to the un-cross-linked monomeric band migrating at ~70 kDa was calculated for each rHA and time point and plotted as function of storage time below.