Identify the downstream targets of Stat3 by using an engineered mouse ES cell line treated with GCSF and LIF plus PD0325901

To identify downstream targets of Jak/Stat3 pathways without being distracted by differentiation signalings from MEK/ERK pathway, we exploited a engineered B6 cells, which stably stably expressing a chimeric receptor (GRgp-Y118F). The chimeric receptor can induce the phosphorylation of Stat3 by GCSF without activating the MEK/ERK pathway. To mimic the effect of GCSF, the chimeric B6 cells were also treated with LIF plus a selective MEK chemical inhibitor, PD0325901, to induce LIF/Jak/Stat3 but MEK/ERK pathways. mESCs starved in serum free growth medium for 6hrs were treated with GCSF or with LIF plus PD0325901 for 1hr, after which total RNA was extracted for analysis.