We showed that PB01 treatment reverses the radio-resistance via inhibition of EMT in A549R and H460R lung carcinoma cells, and that radio-sensitivity induces ER stress, the ATR-p53-GADD45ɑ axis, and mitochondrial cell death when used in combination with radiation (2 Gy). The gene discussed is GADD45A; the disease is lung carcinoma.