CCL21 and amyotrophic lateral sclerosis: Moreover, these findings reveal for the first time the role of some cytokines that had not been related to ALS yet, including chemokines belonging to the tumor necrosis factor (TNF) and tumor necrosis factor receptor (TNFR) superfamilies (CD30 L, GITR, TRANCE, TROY), chemokine ligands family (6Ckine, MIP-3β) and other cytokines (ALK-1, VEGF-D).