In contrast, CAT is considered to be an antioxidant enzyme, playing a critical role in eliminating ROS and maintaining redox balance, and its protein expression is significantly decreased in non-alcoholic steato-hepatitis (NASH) samples, although the ex vivo CAT activity remains stable, indicating that ex vivo quantitation may not precisely reflect the physiological CAT activity [9]. Here, CAT is linked to metabolic dysfunction-associated steatohepatitis.