It has been reported that Smad2 and Smad3 collaboratively regulate mesoderm formation during embryo development.12, 14 Previously, we found that activation of Smad3 is vitally important for ESCs to maintain their genetic integrity during propagation, as depletion of Smad3 leads mouse ESCs to adopt cancer cell properties.12 To further illustrate how Smad3 contributes to ESC stability, we performed microarray assay to identify genes that show an obvious change after Smad3 depletion. Here, SMAD3 is linked to cancer.