Number of rears (A) and locomotor activity (B) of 2-, 4-, and 6-month-old wild-type (open bars) and knock-in mice (filled bars). The data are the mean ± SEM of the total number of rears (A) and lines crossed (B) in 15 min (n = 12–13 per group). *p < 0.05, **p < 0.001 when compared with wild-type mice at the same age; #p < 0.05,##p < 0.005,###p < 0.0001 compared with 2-month-old wild-types (ANOVA followed by Fisher PLSD tests).