CTSS and idiopathic interstitial pneumonia: Kasabova et al. observed that the silencing of cathepsins B or L reduced a-SMA expression; both proteases may be involved in TGF-β1-driven fibroblast differentiation in IPF [34], suggesting that impairment of the cathepsins-dependent proteolytic activity could induce excessive accumulation of collagens and ultimately ECM deposition in the lung.