mEH has been identified as playing a large role in the detoxification and bioactivation of a wide variety of substrates, such as polycyclic aromatic hydrocarbons (PAHs), which are known for their carcinogenic properties.

[15] After hydrolysis, the substrate is then released from its bond to the aspartic acid residue, liberating the diol product from the enzyme active site.

mEH does not catalyze the hydrolysis of bulkier molecules, as their large side-chains may sterically disrupt the charge relay system responsible for water activation.

[18] Microsomal epoxide hydrolase serves as a protective enzyme against potentially harmful small molecules derived from the external environment.

[19] This hydrolysis of genotoxic epoxides causes subsequent effects in several signal transduction pathways, rendering this enzyme important to metabolism.

[1] mEH detoxifies reactive epoxides that are commonly caused from cigarette smoke, and as such it is hypothesized that mutations in EPHX1 in humans may have an effect on an individual's susceptibility to COPD, emphysema and lung cancer.

[1] The role that mEH plays in lung cancer and COPD is still not fully elucidated, as the data on the topic in the literature is not completely unanimous.

[33] Based on the most potent inhibitors characterized, an amide with a bulky alpha-substituent and a phenyl ring with lipophilic groups at meta-positions appear to be key pharmacophore units.