RAN and amyotrophic lateral sclerosis: Likewise, the appearance of a 17 kDa post-translationally modified form of RanGTPase in the drug target isolated from ALS patient PBMCs (Fig. 3 and Table 1) suggests a complex biology connected to TDP-43 mislocalization, in view of the crucial role of RanGTPase in nucleo-cytoplasmic transport.