Glioma cells exhibit an increasing MIF expression under higher cell densities. The glioma cell lines LN18 and LN229 were plated at increasing cell densities. They display a much higher MIF protein content at high cell densities (B). The MIF mRNA expression was not affected by cell density in the LN18 cells, but was reduced in LN229 cells (A). Extracellular MIF levels remained constant (LN229) or increased (LN18) with cell density (C). MIF mRNA expression ratios relative to 18S RNA and MIF protein expression ratios relative to Actin were calculated from four independent experiments.