show severe expression defects in Bptf mutant embryoid bodies compared to controls (Figure 3C). In contrast to the large differences in expression of mesoderm and endoderm markers we observed less than two fold changes in expression of cell cycle regulators and pluripotency markers with the exception of Cyclin D1 (Figure S16A, Figure S16B). These defects in transcription and differentiation were rescued for two independent knockout lines by retargeting exon 2 to the BptfΔExon2 locus using the targeting vector. Our ability to rescue the expression defects of T, Gsc, Sox17 and Cer suggest that the observed phenotypes are due to Bptf mutation (Figure S17A, Figure S17B, Figure S17C) (data not shown). Taken together these results suggest that Bptf is essential for the formation of mesoderm, endoderm and more differentiated ectoderm lineages in the embryoid body.
