In an asymmetric two-dimensional electron gas system, the Rashba effective field arises due to the intrinsic electric field. Even without ferromagnetism, the Rashba spin splitting acts as a source of spin polarization and affects the transport property of the two-dimensional electron channel. In this Rashba channel, the magnetoresistance is determined by the vector alignment between the applied field and the bias current. In addition, the channel resistance for the parallel alignment between the applied field and the Rashba field is much smaller than that for the antiparallel alignment between them, which surprisingly agrees with the spin polarization induced by the Edelstein effect. This anisotropic magneto resistance also allows us to estimate the spin polarization in a two-dimensional quantum well channel. (C) 2017 Elsevier B.V. All rights reserved.