(A) Retention performance of homozygote (IAP+/+, n = 13), heterozygote (IAP+/−, n = 11), and IAP knockout (IAP−/−, n = 17) mice in an inhibitory avoidance learning task. Data are expressed as median ± interquartile range. The comparisons between IAP+/+ and IAP−/− groups, as well as between the IAP+/− and IAP−/− groups, were significant (both P < 0.05, Mann-Whitney one-tailed U test. (B) Locomotor activity level of the same mice measured in a digiscan activity monitor for 20 min (P > 0.05). (C) Endurance time of the same animals measured in a rotarod treadmill (P > 0.05). Data are expressed as mean ±s.e.m. in B and C.