Shen et al. found that knockdown of HDAC4 effectively inhibited renal fibrosis through the following mechanisms: the inhibition of EMT-related pathways (TGF-β/SMAD3, STAT3, ERK1/2 pathways), inhibition of cell cycle arrest, attenuation of apoptosis, and retention of KLOTHO protein [114]. Here, SMAD3 is linked to renal fibrosis.