An SMN2 splice modulator; enhances SMN2 splicing activity by stabilizing the snRNP-SMN2 pre-mRNA complex; increases the expression of the full-length SMN2 transcript at 3-20 mg/kg; increases SMN protein levels in the brain and spinal cord in the C/+ mouse model of SMA at 0.3-30 mg/kg; increases survival of SMNΔ7 mice at 1 and 3 mg/kg