(a) Western blot showing expression levels of DNMT1, 3a and 3b in E14 and P7-ESCs cultured in serum/LIF. Tubulin is shown as loading control. (b) Tet1, Tet2 and Tet3 expression levels measured by RT-qPCR. Values were normalized to Actin mRNA and represent the average of two independent experiments. Average values of two independent experiments. Unprocessed original scans of immunoblots are shown in Supplementary Figure 6.