To further explore the role of Bptf in cell differentiation we generated Bptf knockout mouse ES cells and examined their development in vitro and in vivo. By gene targeting and transient Cre expression we were able to generate eight independent homozygous BptfΔExon2 knockout ES cell lines with a euploid karyotype (Figure S12A). We observed varying degrees of reduced Bptf transcript levels by Northern blotting in mutant cell lines compared to that of wild type controls (Figure S12B). An analysis of BptfΔExon2 mRNA from exons 1 to 8 in wild type and knockout cell lines shows the message to be out of frame resulting in no observable protein in the knockout cell lines (Figure S12C, Figure S12D) (data not shown).
