Both data and statistical analyses were carried out with Igor Pro (WaveMetrics, Inc., Lake Oswego, OR) and Prism (GraphPad Software, Inc., La Jolla, CA) software packages, respectively. The acquired curved fits (using the Hill equation) for each data set were compared employing an F test with a P value < 0.05 considered statistically significant. Further, the plotted data shown in Figure 1 was compared employing a two-tailed, unpaired t test with a P value < 0.05 considered statistically significant.