Upregulations of ER stress-associated genes such as protein kinase R (PKR)-like endoplasmic reticulum kinase (PERK), transcription factor 6 (ATF4), transcription factor 6 (ATF6), growth arrest and DNA damage 34 (GADD34) and inositol requirement 1 (IRE1) might contribute to adaptive survival signaling in cancer cells during radiotherapy [16]. The gene discussed is ERN1; the disease is cancer.