Using the non-parabolic and anisotropic Ogg-McCombe effective Hamiltonian, we study the effect of the Dresselhaus spin splitting on the cyclotron effective mass and Landeg-factor associated to conduction electrons in GaAs-(Ga,Al)As quantum wells under applied magnetic fields, both along the growth- and in-plane directions of the heterostructure. Theoretical results are found in good agreement with available experimental measurements.