Fig. 4.

In vivo administration of Stat3 inhibitor reduces phosphorylation of Stat3 in the LE in response to LIF. Mice were given intrauterine injections of PBS (control) in one horn and Stat3 inhibitor (Stat3pi) in the other on day 3 of pregnancy. LE was isolated on day 4 (noon), allowed to recover in culture for 3 h, and then stimulated for 15 min with LIF to assess the response of Stat3. (A) Relative levels of phospho-Stat3 and total Stat3 in the samples were determined by Western blotting, followed by densitometry with the phosphoimager, and the ratio is shown below each sample. (B) Stat3 inhibitor reduced Stat3 phosphorylation after LIF stimulation by an average of 32% 18 h after in vivo administration of the inhibitor (P < 0.04).