FIGURE 1.

Differences between membrane lipid composition and organization in normal vs MDR cancer cells. In cancer cells PS and PE, mainly confined in the inner leaflet of the membranes, are present in high concentrations in the outer leaflet. Cancer cells have also higher concentrations of cholesterol and consequently an increase in membrane thickness and rigidity is observed. Increased levels of saturated fatty acyl chains in membrane lipids have been associated to the presence of more lipid rafts while low amount of ceramide in MDR cells is a consequence of the low activity of SMase or of the increased SM levels. Changes in lipid composition of the outer membrane of cancer cells are also correlated to a more acidic extracellular pH.