Effects of mechanical stress on STAT3 phosphorylation and LIF expression. STAT3 phoshorylation levels were determined by western blot analysis (A) and lif mRNA expression levels were analyzed by quantitative real time RT-PCR (B) in HC11 cells subjected to 20% RSA for the indicated times. In (A) and (B), analysis were performed by triplicate in three independent experiments. Data are expressed as means ± SE. Significant differences: (*) p < 0.05 compared with 0 min and (**) p < 0.05 comparing cells stretched for 6 h with its corresponding control (grey bar). LIF expression levels quantified by ELISA in the conditioned medium (CM) of cells subjected (S) or not (C) to 20% RSA for the indicated times. Results are expressed in ng/ml and represent the mean ± S.E. of three independent experiments. Significant differences: (*) p < 0.05 compared to their corresponding control and to CM of cells stretched for 8 h (C).