  When an experimentalist or a biological mechanism applies an external force
onto a cell chemically sticking to its substrate, a reacting 'suction' force,
due to the slow penetration of the surrounding fluid between the cell and the
substrate, opposes to the dissociation. This force can overcome other known
adhesive forces when the process is sufficiently violent (typically 100000pN).
Its maximal contribution to the total adhesive energy of the cell can then be
estimated to 0.002 J/m2. The physical origin of this effect is quite simple,
and it may be compared with that leaning a 'suction-cup' against a bathroom
wall. We address the consequences of this effect on (i) the dissociation
energy, (ii) the motion of the fluid surrounding the cell, more especially, on
the pumping of the fluid by moving cells, and (iii) the inhibition of cell
motion.
