Fig. 7.

LIF induces STAT3 phosphorylation. E13 explants were infected with EGFR virus (A, B) or STAT3 virus (C, D), dissociated 4 d later, stimulated with LIF for 20 min, and then stained with antibodies to phospho-STAT3 (A, C) and viral markers (B, D).E, The proportion of cells that respond to LIF by phosphorylating STAT3 (pSTAT3) is greater among EGFR-infected and STAT3-infected cells compared with control-infected cells at E11 and E13. −, No LIF; +, addition of LIF. *p ≤ 0.01; **p < 0.0001, comparing LIF with no LIF. More EGFR-infected and STAT3-infected cells responded to LIF at E13 than at E11 (p < 0.0025).