Western blot analysis of candidate genes mis-regulated in Smad4 null ES cells. A. Id1 expression levels are 7-fold lower in Smad4 null (FNN/BNN) cell lysates in comparison with wild-type (CCE/CCB) ES cells. Id1 protein levels were normalised to β-tubulin expression. HeLa, a human epithelial adenocarcinoma cell line, and the human embryonic kidney line, HEK293, were used as positive controls. B. Hic-5 protein levels are reduced in Smad4 null (FNN/BNN) in comparison with wild-type (CCB/CCH) ES cell lysates. C. Elevated phospho-Paxillin expression by Smad4 deficient ES cells. J558L, a myeloma cell line and embryonic fibroblasts, SNH, were used as negative and positive controls, respectively.