this inhibition persisted for the 24 hours during which the measurement took place. It should be noted, however, that estimates of the duration of this inhibition are not certain, because of apparent enzymatic degradation and substrate degeneration in the control wells late in the experiment, which can be seen in the graph. Test well 5, which was exposed to xenon, only had a 96% inhibition of furin, compared to the 99% inhibition in the other three wells. This variation can be seen more clearly in Figure , which compares enzymatic activity on a logarithmic scale. The cause of this variation may be due to decreased exposure to xenon for the furin in that well secondary to uneven mixing, or perhaps to another unknown cause.