On the basis of previous reports in which RGMa signals regulate small GTPases, such as Rho, Rac, and Ras (2), resulting in the alteration of actin dynamics (8, 9, 32), and abnormal actin kinetics could be a starting point for ALS pathogenesis (30, 33), we tested whether the positive effect of the anti-RGMa antibody observed in the present animal study could be attributed to the modulation of actin dynamics. This evidence concerns the gene RGMA and amyotrophic lateral sclerosis.