The cytoskeleton in cancer cells in animals and humans.

Immunofluorescent staining of human cancer cells with antibodies against actin and myosin shows an important increase of brightness when compared with staining of normal cells from control tissues. Electron microscopic examination of cancer cells shows accumulation of cytoplasmic microfilaments (40--80 A in diameter) with some larger filaments (100--120 A in diameter) scattered in between compared to normal cells from control tissues. Such filaments are particularly abundant at the cell periphery. These findings indicate that the cytoplasmic contractile apparatus of cancer cells is more developed than that of normal cells. Such development may at least in part explain the invasive activity of malignant cells.