SPP1 and pulmonary fibrosis: We have previously shown that two NF-κB-regulated genes, Timp1 and Opn, are significantly induced by MWCNTs in the lung during fibrosis development, and both TIMP1 and OPN play critical roles in promoting MWCNT-induced lung fibrosis (Dong and Ma, 2017a; Dong and Ma, 2017b).