Effect of calcium-chelating EGTA on the average Young's modulus of Ecadbead-cell contact, for cells with intermediate adhesion areas on FN patterns (150 < A< 300 μm2). In control conditions (−EGTA), E increases with incubation time τ, whereas E remains constant at a low value, independent of τ, when EGTA is added. The averaged Young's modulus for beads carrying no Ecad fragments (anti-Fc beads) is also shown at τ = 5 min (150 < A< 300 μm2). These controls demonstrate the specificity of Ecad-Ecad interactions in contact dynamics. Error bars indicate standard error; ∗p<0.08 ; ∗∗p<0.002; ∗∗∗p < 0.00002 (Student's t-test).