GPX4 and colorectal cancer: In conclusion, our results suggest that okanin inhibits the growth of the HCT116 colorectal cancer cells in vitro and in vivo by targeting at and thus suppressing the enzymatic activity of PRDX5 via direct activity inhibition or protein ubiquitination degradation, which results in ROS production and GPX4 ubiquitination degradation that lead predominantly to apoptotic and ferroptotic cell death, respectively (Figure9).