Fig. 4. uPA induces activation and nuclear translocation of Stat3 in MCs. (A) Quiescent MCs were treated with 10 nM uPA for the indicated times and phosphorylated Stat3 protein was visualized in cell lysates by immunoblotting with specific anti-(P)-Tyr-Stat3 antibodies. MCs incubated in medium without uPA served as a control. The middle panel demonstrates the amount of total Stat3 loaded on the gel for each sample. Results are representative of three independent experiments. Quantification (mean ± s.e.m.) of the results of these experiments by densitometry is shown below. Significance between control unstimulated and stimulated cells was determined by Student's t-test (*P<0.05). (B) A subconfluent MC monolayer was treated with 10 nM uPA at 37°C or left untreated, fixed and stained using primary anti-(P)-Tyr-Stat3 antibody and the corresponding Alexa Fluor-488 secondary antibody. The data are representative of three separate and independent experiment performed in duplicate for each condition.