Figure 6.

Erk2 CKO mice are aggressive and impaired in maternal behaviors. A–C, Maternal nurturing in newly postpartum Erk2 CKO mice. A, In nurturing analysis of postpartum females, a mother is deprived of her first litter of pups for 10 min and then rechallenged with three pups placed individually in the corners of her cage. The typical behavior of a control mother is shown, approaching one pup immediately and collecting all three pups into one corner within a short latency (left), then crouching over them. The Erk2 CKO mother typically ignores the pups and does not retrieve them immediately (right). B, Time spent crouching over the pups in the nest of control (n = 10) and Erk2 CKO (n = 10) mothers. C, The percentage of scattered pups from the same set of mothers as in B. D–F, Aggressive behaviors of male Erk2 CKO mice as measured by the resident-intruder test (control, n = 7; Erk2 CKO, n = 7). **p < 0.01, ***p < 0.001.