S1036

U0126 [1,4‐Diamino‐2,3‐dicyano‐1,4‐bis (o‐aminophenylmercapto) butadiene, Selleck #S1102), PD0325901 (Selleck #S1036) or Trametinib (Selleck #S2673) were applied. See Appendix S1 for details.

Mouse ESC were grown on 0.1% gelatine-coated plates at 37 °C and 5% CO₂, in a serum-free medium made of KnockOut Dulbecco’s modified Eagle medium (KO-DMEM, Gibco 10829018), supplemented with 15% KnockOut Serum Replacement (KSR, Gibco 10828028), 2 mM L-Glutamine (Gibco 25030081), 1 mM non-essential amino acids (NEM NEAA, Gibco 11140076), 100 µM β-mercaptoethanol (Gibco 21985023) and 1x Antibiotic-Antimycotic (Gibco 15240062). They were maintained in a pluripotent state by using ESGRO Leukemia Inhibitory Factor (LIF 1 µM, Millipore ESG1106) and two inhibitors (called 2i), PD0325901 (MEK inhibitor 1 µM, Selleckchem S1036) and CHIR99021 (GSK-3 inhibitor 3 µM, Selleckchem S2924) to block the MAPK/ERK and glycogen synthase kinase 3β (GSK-3β) pathways.