Bromodeoxyuridine (BrdU) is a thymidiie analogue that incorporates into DNA of dividing cells during the S-phase of the cell cycle. Previous work in laboratories reported that treatment with lOyM BrdU in the human lung carcinoma cell line (DLKP) resulted in increased expression of the cytoskeletal proteins Keratin 8 and 18 and the cell adhesion proteins a2 and b1 integrin. This study investigated protein expression changes in differentiating DLKP cells following exposure to 10yM BrdU. DLKP cells were grown in culture flasks and harvested after 7 days exposure to BrdU. Two-dimensional gel electrophoresis was used to investigate BrdU specific changes in the proteome of DLKP BrdU treated and control cells. Cy3-labeled DLKP control were combined with Cy-5 labeled BrdU DLKP treated proteins and separated on the same 2-D gel along with a Cy-2 labelled mixture of both samples as an internal standard. Using DIGE technology, the statistically significant comparisons of each protein abundance was made over three biological replicates. 43 protein spots were identified as differentially regulated. Among the 43 protein spots, 25 were found to be up-regulated and 18 were found to be downregulated.