To investigate the underlying mechanism by which increasing BMP3 could attenuate the progression of pulmonary fibrosis, we isolated primary pulmonary fibroblasts from 21-day bleomycin-induced mice (21 day's fibroblasts) and saline-instilled mice (Normal fibroblasts) according to the method described in a previous study [39]. This evidence concerns the gene BMP3 and pulmonary fibrosis.