S100A4 and amyotrophic lateral sclerosis: To investigate whether an augmented expression of S100A4 is a common trait of fibroblasts derived from patients with ALS, we have analyzed the protein expression in primary fibroblasts from ALS patients without known variants in ALS-associated genes, and from patients carrying pathogenic C9orf72 expansions, the most common cause of familial and sporadic ALS found to date.