In the present study we screened 17 members of the cytokine family (IL-1β, IL-2, IL-4, IL-5, IL-6, IL-7, IL-8, IL-10, IL-12 [p70], IL-13, IL-17, granulocyte colony-stimulating factor [G-CSF], granulocyte-macrophage colony-stimulating factor [GM-CSF], IFN-γ, monocyte chemoattractant protein [MCP]-1, macrophage inflammatory protein [MIP]-1β and tumour necrosis factor [TNF]-α) in breast cancer tissues. The gene discussed is IL4; the disease is breast cancer.