Iec 6

Rat jejunal crypt cell line IEC‐6 and HIEC line were purchased from the Cell Bank of the Chinese Academy of Sciences (Shanghai, China) as reported previously.⁵¹, ⁵² The cells were placed in Dulbecco's modified Eagle's medium (DMEM) supplemented with 10% FBS (v/v; Gibco, Grand Island, NY) and 1% (v/v) penicillin–streptomycin (Beyotine, Nantong, China) at 37°C with 5% CO₂. For IEC‐6 cells, 10 μg/ml recombinant human EGF (Gibco) and 10 μg/ml bovine insulin (Yeasen, Shanghai, China) were added. For ionizing irradiation, an X‐ray linear accelerator (RadSource, Suwanee, GA) at a fixed dose rate of 1.15 Gy/min was applied.

Rat jejunal crypt cell line IEC-6 was purchased from the Cell Bank of the Chinese Academy of Sciences (Shanghai, China), and maintained in Dulbecco’s modified Eagle’s medium (DMEM) supplemented with 10% (v/v) heat-inactivated fetal bovine serum (FBS) and 1% (v/v) penicillin-streptomycin (Hyclone, Logan, USA) at 37 °C in a humidified atmosphere containing 5% CO₂. IEC-6 cells were seeded onto a 96-well plate at a density of 1 × 10⁴ cells/well. After a 24-h incubation, the medium was replaced by fresh medium containing 1 μM of purified recombinant EGFP (Sangon Biotech, Shanghai, China) or NeuroD-EGFP protein. After five hours, the cells were washed twice by PBS. The cells were counterstained with 4,6-diamidino-2-phenylindole (DAPI; Sigma-Aldrich, St. Louis, USA) and imaged under a confocal microscope.