This gene 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. This enzyme is the major liver enzyme and functions in liver drug clearance. The expression and activity of this gene is age-related but independent of growth hormone level. This gene is clustered with Ces7 and Ces3 on chromosome 8. [provided by RefSeq, Jun 2010]