Our previous study found that blocking ubiquitin carboxyl-terminal hydrolase-L5 (UCHL5) activity using a deubiquitinating enzyme (DUB) inhibitor, bAP15, inhibited the phosphorylation of Smad2/Smad3 and TGF-β1 signaling in a concentration-dependent manner and induced apoptosis in ovarian cancer cells [27]. This evidence concerns the gene SMAD2 and ovarian cancer.