The quantum Hall effect in a single-layer graphene sample is studied in strong magnetic fields up to 28 T. Our measurements reveal the existence of a metal- insulator transition from filling factor $ u=-2$ to $ u=0$. The value of the universal scaling exponent is found to be $kappa=0.57 $ in graphene and therefore in a truly two-dimensional system. This value of $kappa$ is in agreement with the accepted universal value for the plateau-insulator transitions in standard quasi two-dimensional electron and hole gases.
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