Also, IVIG may stimulate the production of IL−12, an anti-tumor and anti-angiogenic cytokine, enhance NK cell activity [31], and can decrease the level of matrix metalloproteinase−9 (MMP−9) expression in the U937 monocyte line with a decrease in the m-RNA level of MMP−9, a vital step in the invasion of metastatic cancer cells. The gene discussed is MMP9; the disease is cancer.