Figure 1
From: Long-term stability of recombinant tissue plasminogen activator at -80 C
tPA activity versus sample age for the data. The solid circles denote the average activity for all samples at the given sample age, and the error bars are the 95% confidence limits. The individual data points are the mean tPA activity values for a given concentration; the values are shown in the legend. Overall, there is no decline in tPA activity over time.