Derivation of Mouse Embryonic Stem (ES) Cell Lines Using Small-Molecule Inhibitors of Erk and Gsk3 Signaling (2i).

The efficiency of embryonic stem (ES) cell derivation is very high if embryos are incubated, from the eight-cell stage, in the presence of the two inhibitors of signaling via the Erk and Gsk3 pathways (PD0325901 and CHIR99021, respectively, known as "2i"). The success rate may vary, depending on the quality of the embryos and the speed with which they are processed, but it is not unusual to obtain ES cell lines from all embryos allocated to the study, even from the least permissive strains. Furthermore, ES cells can be efficiently obtained from any complex genetic mouse model or for in vitro analysis and additional genetic manipulation in any background of choice.