Fibronectin is not a serum spreading factor for HeLa cells.

The spreading of HeLa cells on plastic substratum is mediated by fibronectin-depleted foetal calf serum but not by fibronectin isolated by gelatin-Sepharose affinity chromatography. The same is true for freshly explanted chick embryonic chondrocytes. In contrast, BHK cell spreading exceeds 67% after 120 min at 37 degrees C in fibronectin-supplemented (10 micrograms ml-1) serum-free medium. Long-term cultivation of HeLa cells in Eagle's MEM supplemented with fibronectin-free serum is associated with the accumulation of cells in mitosis or before cytokinesis; many cells die and the remaining living cells, characterized by marked changes in morphology, multiply very slowly. It can be concluded therefore that fibronectin does not produce spreading in HeLa cells but forces them into mitosis.