LTB4, 5-HETE, and 5-oxoETE may contribute to the innate immune response as leukocyte chemotactic factors, i.e. they recruit and further activate circulating blood neutrophils and monocytes to sites of microbial invasion, tissue injury, and foreign bodies. When produced in excess, however, they may contribute to a wide range of pathological inflammatory responses (see 5-HETE and LTB4). 5-Oxo-ETE is a particularly potent chemotactic factor for and activator of eosinophils and may thereby contribute to eosinophil-based allergic reactions and diseases (see 5-oxo-eicosatetraenoic acid). These metabolites may also contribute to the progression of certain cancers such as those of the prostate, breast, lung, ovary, and pancreas. ALOX5 may be overexpressed in some of these cancers; 5-Oxo-ETE and to a lesser extent 5-HETE stimulate human cell lines derived from these cancers to proliferate; and the pharmacological inhibition of ALOX5 in these human cell lines causes them to die by entering apoptosis. ALOX5 and its LTB4 metabolite as well as this metabolite's BLT1 and BLT2 receptors have also been shown to promote the growth of various types of human cancer cell lines in culture.