Like bleomycin challenged Ppp1r15a−/− mice, wt mice treated with Sephin1 had significantly increased lung fibrosis at day 21 compared with the vehicle control treated mouse group, as measured by lung tissue hydroxyproline (Fig. 6a), and whole lung gene expression of Col1a2 (Fig. 6b). Here, PPP1R15A is linked to pulmonary fibrosis.