SMN1 and proximal spinal muscular atrophy: Further screens have identified that flunarizine, a calcium channel blocker, can alter splicing events in HeLa cells, including intron retention in SMN.48 This was confirmed in a screen on SMA patient fibroblasts, where flunarizine increased localization of SMN to Cajal bodies and improved the survival of spinal cord motor neurons from SMA mice.50