Western blotting analysis was conducted as previously described (25 (link)). Cells were lysed with RIPA lysis buffer, and total protein concentrations were quantified using Protein Assay Kit (Bio-Rad, Hercules, CA, USA). Equal amounts of protein were separated on Mini-PROTEAN TGX gels (Bio-Rad) and transferred onto PVDF (polyvinylidene fluoride) membranes (Millipore, Billerica, MA, USA). After blocking with 5% BSA at room temperature for 30 min, the membranes were incubated with the relevant primary antibody followed by an appropriate secondary antibody. The primary antibody of p38, p-p38, MAPKAPK2, p-MAPKAPK2, HSP27 and p-HSP27 were obtained from Cell Signaling Technology (1:2000, Danvers, MA, USA). CNR1 and CNR2 antibody were purchased from Abcam (1:800, Cambridge, MA, USA). Anti-GAPDH (1:10000, Cell Signaling Technology) was used as the loading control. Western blots were developed using ECL reagent (Pierce ECL Western Blotting Substrate, Thermo Scientific).