Average cell traction force within a hard substrate of 30 kPa and 45 kPa stiffness.

<p>Average cell traction force, </p><p></p><p></p><p><mi>F</mi>nettrac</p><p></p><p></p>, versus time within hard substrates during MSC differentiation and osteoblast proliferation. Points A represent the instant of MSC differentiation to osteoblast which instantly causes a traction force increase while points B are the initial instant of osteoblast proliferation causing a jump in the average net traction force.<p>