WEE1-inhibition sensitizes OS cells to γ-irradiation but not normal cells. (A) Indicated are dose response curves of irradiated cells (squares) and cells treated with IR + WEE1-inhibitor (triangles). The curves represent three experiments, performed in triplicate; error bars indicate standard deviation (SD). The sensitizing effect of WEE1 inhibition is significant in all three OS cell lines (student's t-test: p < 0.01) (B) Analysis of cell viability of human OS cell lines and human primary osteoblasts treated with 4 Gray (Gy) IR in the presence or absence of WEE1-inhibitor. Bars represent experiments performed in triplicate; error bars indicate SD. The OS cell lines MG-63, U2OS and SaOS-2 show a 2-fold decrease in cell viability when treated with combination therapy, whereas human primary osteoblasts ORT-1, Hum31 and Hum54 do not show sensitization to radiotherapy in the presence of the WEE1-inhibitor.