Previously described procedures were used [21 (link), 22 (link)]. Briefly, protein samples (50 μg) were separated using NuPAGE 4–12% Bis-Tris gels (Life Technologies, Carlsbad, CA, USA). Proteins were transferred to polyvinylidene difluoride membranes, which were then blotted with primary antibodies overnight and visualised using ECL Plus substrate (Thermo Scientific, Waltham, MA, USA). The density of the bands was quantified using Quantity One 1-D Analysis Software (Bio-Rad Laboratories, Hercules, CA, USA). Trizol (Life Technologies) was used to isolate total mRNA. Relative PCR quantification was performed using a Stratagene Mx3000P (Agilent Technologies, Santa Clara, CA, USA). Expression data were normalised to the amount of 18S rRNA.