In this project we aimed to isolate novel factors involved in the early stages of mouse neural precursor cell differentiation from embryonic stem (ES) cells using Difference Gel Electrophoresis (DIGE). Six proteins were identified using mass spectrometry and these were found to be associated with the control of the cell cycle, stress response, mitochondrial function and the cytoskeleton. The behaviour of two of these proteins has been characterised further and we demonstrate that early ES cell differentiation toward a neural fate is characterised by depletion of Hsp25, a small heat shock protein, and in association with particular cell populations, an appearance of positive nuclear staining for Prohibitin, a protein normally shown to localise to mitochondria.