Studies with cultured human cells have found that there are a large number of ALOX5 mRNA splice variants due to alternative splicing. The physiological and/or pathological consequences of this slicing has yet to be defined. In one study, however, human brain tumors were shown to express three mRNA splice variants (2.7, 3.1, and 6.4 kb) in addition to the full 8.6 lb species; the abundance of the variants correlated with the malignancy of these tumors suggesting that they may play a role in the development of these tumors.