To characterize the human macrophages in HSC-NOG-hIL-6 Tg mice further, we examined the expression of IL-4Rα in human macrophages, as IL-4 is one of the factors supporting the differentiation of TAMs and expression of the IL-4 receptor is a marker for delineating TAMs in tumor (42, 43). This evidence concerns the gene IL4 and neoplasm.