*2.5. FACS Analysis for CD44/24 and ALDEFLUOR Assay*

Cells were irradiated with the specific doses of radiation and then stained with anti-CD44-APC and anti-CD24-PE with their respective isotype controls, incubated for 40 min and analyzed on a *FACSCanto*™ flow cytometer (BD). To measure ALDH activity, cells were analyzed by an ALDEFLUOR assay kit (STEMCELL Technologies), following the manufacturer's protocol. Flow cytometry was performed on a *FACSCanto*™ flow cytometer (BD), USA and analyzed by DIVA software (BD Biosciences, USA).

#### *2.6. Immunoblotting*

Protein extracts were prepared, and immunoblotting was performed, as described previously [15], using the following antibodies: Nrf2, Bach1, SNAIL and SLUG (Abcam, Burlingame, CA, USA); NQO1, HO1 (Santa Cruz, TX, USA), Keap1, SOX2 and KLF4, NANOG (Cell Signaling Technology, ((Danvers, MA, USA); BAX and BCL2 (Santa Cruz, Dallas, TX, USA) at 1:1000 and GAPDH (1:10,000, Sigma). Primary antibodies were detected using secondary antibodies (1:10,000, Bio-Rad), conjugated with HRP, and protein–antibody complexes were detected by the Substrate Detection Kit (Thermo Fisher, CA, USA). Densitometry was performed using the Image Lab and Image J software. GAPDH was used as loading control for whole-cell lysates.
