Biochemical analysis of cell adhesion to a substratum and its possible relevance to cell metastasis.

The evidence is reviewed that two types of cell attachment occur, depending upon the presence or absence of serum in the medium. In the absence of serum, attachment has many characteristics of a nonphysiological process. In the presence of serum, attachment occurs as a series of steps: adsorption of serum components onto the substratum, contact between the cell and substratum, initial attachment, and progressive attachments leading to cell spreading. Although there is a close interdependence of these events, they could be experimentally distinguished. Studies are reported indicating that cell spreading requires the adsorption of a specific serum glycoprotein onto the substratum surface. The relationship between cell adhesiveness and the altered behavior of malignant cells is discussed.