Comparison of real time PCR result upon differentiation and activation between primary monocytes and U937 cells. (Upper panel) Up regulation of CD11b alone but not of CD14 was observed with U937 cells differentiated with PMA. Prominent induction of TNFalpha after LPS stimulation was seen with both cell types. (Lower panel) Up regulation of CD14 and CD11b surely indicates maturation and activation of primary macrophages (M-CSF macrophages). Down regulation of TNFalpha upon macrophage differentiation reflects intrinsic abundance of mRNA with in vivo monocytes on the contrary to U937 cells. Mature macrophage stage was indicated by black bar (denoted as PMA/U937 cells or M-CSF macrophages). Activated macrophage stage was indicated by white bar (denoted as LPS). Error bars represent technical variation. RQ (relative quantification) = 2-ddCt.