In order to elucidate the mechanism of the anti-tumour action, the effect of CV-6504 on the metabolism of AA through the 5-, 12- and 15-lipoxygenase pathways has been determined in cell lines sensitive (MAC16, MAC13, MAC26 and Caco-2) and resistant (A549 and DU-145) to CV-6504. The gene discussed is ALOX15B; the disease is neoplasm.