Fig. 6

LKB1 increased the radiosensitivity of A549 and H1299 cells. The radiosensitivity was evaluated by clonogenic cell survival assay. a, b A549 cells were transfected with EGFP or EGFP-LKB1, and H1299 cells were transfected with shCtrl or shLKB1, and all were irradiated with the indicated dose. After 14 days, the colonies formed by the surviving cells were counted. The survival fraction was normalized to the non-irradiated controls and presented as mean ± SD. The survival curves were fitted to a linear-quadratic model using GraphPad Prism 5.0 software. Re-expression of LKB1 in A549 cells increased the sensitizer enhancement ratio (SER) to 1.23, whereas knockdown of LKB1 in H1299 cells decreased the SER to 0.83