UCHL5 also known as UCH37 is a 329 amino acid protein that plays a crucial role in the 19S regulatory complex of the 26S proteasome, where UCH-L5 functions to edit polyubiquitinated protein substrates. UCH-L5′s ability to rescue ubiquitinated proteins, including those with oncogenic potential, from proteasomal degradation highlights UCH-L5′s importance in cellular regulation and tumor biology. Notably, UCH-L5 interacts with Smad7, leading to a significant upregulation of TGFβ-dependent gene expression through the de-ubiquitination and stabilization of TGFβ receptor I. Given that overexpression of UCH-L5 and other deubiquitinating enzymes has been observed in various cancer cell lines, targeting these proteins may offer promising avenues for cancer therapy.