document: To investigate the in vitro synergistic effect of EGFR/IKKα gene silencing and X-ray irradiation, U87MG cells (5,000 cells per well) were treated with 1 μM of TrQβ@b-3WJsiEGFR Let-7g for 72 h followed by 2 Gy X-ray irradiation. After 24 h, the cells were washed with PBS buffer (pH=7.4) and incubated with XTT solution at 37°C for 30 min (n=8). Cell viability was analysed by measuring the absorbance at 450 nm using an SpectraMax M2 microtiter plate reader. Cell viability (%) was defined as the