In addition, our observations revealed that CIK cells secreted significant amounts of IFN-γ and IL-6, and slight amounts of IL-2, IL-4, IL-10 and TNF-α, indicating that IFN-γ and IL-6 might play an critical role in anti-tumor activity of CIK cells against tumor cells, which remains to be fully characterized. This evidence concerns the gene IL4 and neoplasm.