text:  2i_1 2i-adapted mouse embryonic stem cells, CHIR99021(3 μM)+PD0325901(1 μM), LIF is withdrawn for 24 hours treatment: CHIR99021/PD0325901; cell line: 2i-adapated Ctnnb1-Biotin-3xFLAG knock-in ESC line (Ctnnb1-BioFLneo;BirA ESC)