As shown in Figure 4, the expression levels of TGF-β, TGF-βR1, TGF-βR2, p-Smad2, and p-Smad3, which were related to the TGF-β/Smad signaling pathway, were upregulated in the BPH group compared with the control group (P<0.05 or P<0.01). Here, SMAD2 is linked to benign prostatic hyperplasia.