GAP43 and relapsing-remitting multiple sclerosis: Significantly lower CSF GAP-43 concentrations were found in progressive MS [1640 (1120–1950) pg/mL, p = 0.004], but not in relapsing-remitting MS (RRMS) [2270 (1620–2830) pg/mL, p = 0.8], compared with healthy controls (HCs) [2340 (1580–3230) pg/mL] (Fig. 1A).