MAP1B and proximal spinal muscular atrophy: However, despite MAP1B ́s role in cellular structural stability (Oberstadt et al, 2018), MAP1B has been attributed regulatory function in morphology and physiology of synapses (Bodaleo et al, 2016; Tortosa et al, 2011) and is involved in the pathomechanisms of spinal muscular atrophy (Bora et al, 2021).