Sprr3

All lysates were prepared in 2 × Laemmli sample buffer (62.5 mM Tris-HCl, pH 6.8, 25% [v/v] glycerol, 2% [w/v] sodium dodecyl sulphate [SDS], 5% [v/v] β-mercaptoethanol, and 0.01% [w/v] bromophenol blue, Bio-Rad, Hercules, CA, USA). All cellular proteins were quantified using the Bradford solution (Bio-Rad) according to the manufacturer’s instructions. The samples were then separated using SDS-polyacrylamide gel electrophoresis (PAGE) and transferred onto a polyvinylidene fluoride (PVDF) membrane (Bio-Rad). After blocking with 4% (w/v) skim milk in Tris-buffered saline plus Tween (TBST; 25 mM Tris, 140 mM sodium chloride [NaCl], and 0.05% [v/v] Tween^® 20), the membranes were incubated overnight with the following specific primary antibodies: HA (1:3000, Santa Cruz), SPRR3 (1:3000, Proteintech), Actin (1:10000, EMD Millipore), GAPDH (1:10000, Cell Signaling Technology), phosphor-c-Jun (1:1000 Cell Signaling Technology) and c-Jun (1:3000 Cell Signaling Technology). For protein detection, the membranes were incubated with horseradish peroxidase (HRP)-conjugated secondary antibodies and the signals were detected using SuperSignal^® West Dura HRP detection kit (Pierce, Rockford, IL, USA).