10 μg of each sample was loaded on 4%–15% gradient gels (Mini or Criterion TGX™, Bio‐Rad, CA, USA) and subjected to SDS‐PAGE under reducing conditions. Following SDS‐PAGE, proteins were transferred onto PVDF membranes using a semi‐dry technique (TransBlot Turbo™, Bio‐Rad, CA, USA). After transfer, membranes were briefly rinsed in dH