Fig. 4. Early cellular strengthening response to oscillatory force. (A) Schematic of experimental design. Six consecutive 3-second force pulses (130 pN) were applied to bound RGD-beads, separated by brief (4-second) intervals. (B) Representative example of bead displacements measured in response to the pulsatile force regimen shown in A. Note strengthening of adhesions following pulses 2 and 3, as indicated by decreased displacements. (C) Average relative RGD-bead displacements induced by the pulsatile force regimen. Black bars, control; white bars, BDM; gray bars, Y27632; hatched bars, 4°C; ^*P<0.05 where indicated compared with the level in the first pulse respective experimental condition; note that only controls exhibited significant attenuation.