CES2 (carboxylesterase 2) encodes a member of the carboxylesterase large family. The family members are responsible for the hydrolysis or transesterification of various xenobiotics, such as cocaine and heroin, and endogenous substrates with ester, thioester, or amide bonds. They may participate in fatty acyl and cholesterol ester metabolism, and may play a role in the blood-brain barrier system. The protein encoded by CES2 is the major intestinal enzyme and functions in intestine drug clearance. Alternatively spliced transcript variants have been found for CES2.