GSTT1 belongs to the GST superfamily and Theta family. It is a conjugation of reduced glutathione to a wide number of exogenous and endogenous hydrophobic electrophiles. GSTT1 acts on 1,2-epoxy-3-(4-nitrophenoxy)propane, phenethylisothiocyanate 4-nitrobenzyl chloride and 4-nitrophenethyl bromide. It displays glutathione peroxidase activity with cumene hydroperoxide. GSTM1 and GSTT1 has been suggested as a risk factor in various cancers. GSTT1 is important in the detoxification of unidentified xenobiotics in the large intestine.