We have observed Brillouin-enhanced nondegenerate four-wave mixing (NFWM) induced by an acoustic wave and Rayleigh-type NFWM induced by molecular reorientation in CS2. It was found that the acoustic wave and the molecular reorientation grating are not mutually independent. The existence of the acoustic wave destroys the phase coherence between the polarizations of the Rayleigh-type NFWM and the Brillouin-enhanced NFWM.