The effect of low doses of LPS on B16 mouse melanoma migration on matrigel matrix. The insert: the 8-μm 0.3-cm2 membrane was covered with matrigel (approx. 7 μg/cm2). B16 melanoma cells were applied at 4 × 105 cells per insert in DMEM. LPS was applied as a dose gradient (10 U/ml equals 0.25 ng/ml). The concentration of the attracting agent FBS in the lower section of the migration chamber was 7.3–7.5%. Migration was carried out for 7–8 h at 37°C in CO2. The cells were stained and counted under light microscopy on the whole membrane. The mean number of cells per membrane (bars) and SD (lines) are presented.