SMN1 and proximal spinal muscular atrophy: Regarding the mechanism of action of salbutamol in patients with SMA, Angelozzi et al. reported in 2007 that salbutamol promoted transcription of SMN2 and splicing of SMN2 exon 7 in fibroblasts derived from a patient with SMA type I, leading to an increase in intracellular SMN protein [131].