Range of motion about the ankle joint in Zmpste24+/+ and Zmpste24−/− mice from 5 to 20 weeks of age. Data are presented as means ± SE; n = 3 to 13 per genotype per time point. For many data points, the error bars are within the symbols representing the means. Asterisk, within genotype, significantly different than 5 weeks of age. Dagger, within genotype, significantly different than 10 weeks of age. Double dagger, significantly different than Zmpste24−/− mice at corresponding age