Affine semiprime algebras of GK dimension one are (still) pi
  In this note, we give a new proof of the fact that an affine semiprime algebra R of Gelfand-Kirillov dimension 1 satisfies a polynomial identity. Our proof uses only the growth properties of the algebra and yields an explicit upper bound for the pi degree of R. 
Christopher J. Pappacena, Lance W. Small, and Jeanne Wald