Statistical analysis
All the experiments were performed in triplicates. The results of all the experimental data are presented as Mean±SEM. GraphPad Prism version 5.02 was used to do statistical comparisons employing Student’s t-test (San Diego, CA, USA). Mean differences were analysed and * was used to represent the comparison with unstimulated control. Differences were considered significant at *P<0.05, **P<0.01, ***P<0.001.