Foraminifera samples from the deep-sea sediment of an International Ocean Discovery Program (IODP) Site 363-U1489 (2º7.19'N, 141º1.67'E, water depth 3421 m), Western Equatorial Pacific, were measured for the Neodymium isotope composition on the authigenic phases of mixed planktonic foraminifera shells, covering the time-interval from 4 to 2 Ma with an average time-resolution of ~20 ka. The measurements were performed by a ThermoScientific NeptunePlus Multi-Collector Inductively Coupled Plasma Mass Spectrometer (MC-ICP-MS) at LSCE, Gif-sur-Yvette, France, and the results are used to decipher changes in the water-mass circulation of the deep Pacific during the Pliocene-Pleistocene transition.