VAPB and amyotrophic lateral sclerosis type 8: BMP/GDFs have also been implicated in ALS progression via a separate line of inquiry, in that a Drosophila model of familial ALS8 demonstrates disrupted BMP signaling at their NMJs; Thus mutations in VAPB (vesicle-associated membrane protein B) cause ALS8 [9], [10] and altering VapB disrupts BMP signaling at the Drosophila NMJ [11].