Another human CYP4A subfamily member has been identified and designated CYP4A22. This protein is highly homologous with CYP4A11 and has been shown to exhibit lauric acid ω-hydroxylase activity. Expression of CYP4A22 is low in all tissue in which it is found. The CYP4A subfamily is not the only CYP4 family of proteins that have been found to possess ω-hydroxylase activity. The CYP4F family enzyme CYP4F3A, which is expressed in leukocytes, is necessary for the ω-hydroxylation and subsequent degradation of leukotriene B4 (LTB4).