In the BAL fluid from mice with bleomycin-induced lung fibrosis, NEU1, 2, and 4 were not detected, even on over-exposed western blots (Supplementary Fig. S6 a,b and c), while NEU3 was upregulated compared to the BAL fluid from control mice (Fig. 2e and f). Here, NEU3 is linked to pulmonary fibrosis.