CHIT1 and amyotrophic lateral sclerosis: The expression of APOB1 (two peptides), CHI3L1 (three peptides), CHIT1 (four peptides), GPNMB (one peptide), ERAP2 (one peptide), JCHAIN (one of two quantified peptides), SERPINA1 (three peptides), SERPINA3 (two peptides), and UCHL1 (one peptide) were upregulated in ALS patients (Figure 4A), while the expression of APP (three peptides), CAMK2A (three peptides), CLSTN3 (one peptide), FSTL4 (one of two quantified peptides), L1CAM (one peptide), and NPTX2 (two peptides) were downregulated (Figure 4B).