The effects of D156844 and follistatin on the motor phenotype of SMNΔ7 SMA mice. SMNΔ7 SMA mice received either 3 mg/kg/d D156844 and 1 mg/kg/qad follistatin (combo), follistatin, D156844 or vehicle beginning at PND04. Behavior responses were also compared against age-matched healthy littermates (carrier). (A) Proportion of mice exhibiting successful righting reflex responses at PND07 and PND11. (B) Righting reflex latency in treated SMNΔ7 SMA mice. There was an arbitrary cutoff time of 61 s. (C) Spontaneous locomotor activity— measured as the number of grids crossed in 1 min—in treated SMNΔ7 SMA mice. (D) The number of pivots, or 90° turns, made in 1 min in treated SMNΔ7 SMA mice. Key: *, p ≤ 0.05 when compared against vehicle-treated SMNΔ7 SMA mice.