MMP1 and pulmonary fibrosis: Overall, on day 5, neither TGF-β1 nor CdCl2 plus TGF-β1-treated lung slices exhibited significant difference in expressing the genes related with lung fibrosis such as Col 1a1, α-SMA or MMP1, nor did they appear different histology feature in comparison with the untreated lung slices (data not shown).