Kalirin Exon 13 knockout results in growth retardation . A. After breeding into a C57BL/6 background, matings of KalSRKO/+ males and females yielded WT, KalSRKO/+ and KalSRKO/KO progeny in a Mendelian ratio. B and C. After weaning, WT and KalSRKO/KO mice were weighed at regular intervals. Male (B) KalSRKO/KO mice grew more slowly than WT mice. Female (C) KalSRKO/KO mice were smaller at weaning but grew at the same rate as WT mice. Neither male nor female KalSRKO/KO mice grew in a manner identical to WT mice (p<0.0002).