  We measure the effective Lande g-factor of high-mobility two-dimensional
electrons in a modulation-doped AlAs quantum well by tilting the sample in a
magnetic field and monitoring the evolution of the magnetoresistance
oscillations. The data reveal that |g| = 9.0, which is much enhanced with
respect to the reported bulk value of 1.9. Surprisingly, in a large range of
magnetic field and Landau level fillings, the value of the enhanced g-factor
appears to be constant.
