MMP9 and renal fibrosis: For further confirming the effects in vivo of BPP on renal fibrosis described above, we next determined the changes of ECM accumulation and EMT induction by examining the effects of BPPs on the mRNA and protein levels of Collagen I, α‐SMA, MMP9, TIMP1, E‐cadherin, N‐cadherin, vimentin, snail, twist and ZEB1 in HK‐2 cells treated with both BPP and TGF‐β1.