17-P040 The SCF/KIT pathway in differentiating embryonic stem cells

also able to show that Sox3 could interact with Groucho directly. Using cell fractionation, the interacting factors could again be seen to affect each others subcellular distribution. Sox3 and Groucho both appear in the chromatin fraction when co-expressed. The transcriptional activation activity of Sox3 was repressed after coexpressing with Groucho. Using deletions of sox3 we have mapped the groucho interaction domain in the c-terminus. Together, these data suggest that Sox3 could function not only as a transcriptional activator but also as a repressor through interacting with the corepressor Groucho.