To investigate the molecular regulation of intrinsic apoptosis, total protein was extracted from the patient-derived IECs and normal IECs, and western blotting was performed to detect key regulators of intrinsic apoptosis including Bak, Bax and Bcl-2. Bak, Bax and Bcl-2 were detected using HRP-conjugated antibodies and Clarity ECL Western Blotting Substrate from Bio-Rad. The western blotting results are shown in Figure 6.