Cell attachment to collagen: the requirement for energy.

It has previously been demonstrated that cell attachment to collagen depends on the presence of a serum-derived cell attachment factor. Two steps in the cell attachment process have been defined. First, the cell attachment factor can bind to collagen in the absence of divalent cations. Secondly, either Ca++ or Mg++ are required for cells to attach to the collagen-cell attachment factor complex. A third requirement for cell attachment to collagen is demonstrated here; namely, cellular metabolic energy. A simple method for the assay of ATP in tissue culture cells is presented.