The decreased intracellular production of the M1-related cytokine IL-12 and increased intracellular production of the M2-related cytokine TGF-β1 by RAW264.7 macrophages co-cultured with 4T1 tumor cells compared to mono-cultured RAW264.7 macrophages confirmed the M1 to M2 polarization hypothesis, which was further corroborated by secreted cytokine measurements in the culture media. The gene discussed is TGFB1; the disease is neoplasm.