We could confirm that tumour epithelial cells express IL-4 receptors, in line with previous studies using both tumour tissue and cultured cells [29], [36], and could demonstrate that IL-4 increases FAAH activity in a PC-3 and R3327 AT1 prostate cancer cells as well as in P19 teratocarcinoma cells, indicating it to be a rather general effect of this cytokine. This evidence concerns the gene FAAH and neoplasm.