Figure 5

UW228 cells show increased radiation resistance and increased ABC transporter expression after long-term weekly radiation exposure. (A) Enhanced radiation resistance of cells exposed repeatedly to 3 Gy, by resazurin based total viability assay. Cells were assessed for resistance 2.5 weeks after receiving their final treatment dose. Mean survival of 4 long-term independently cultured sub-lines for each treatment shown. Error bars +/− 1 SD, “***” indicates p-value < 0.001. (B) Elevated expression of ABCA1 and (C) ABCG2, in the independent sub-lines, by qRT-PCR. Points represent relative gene expression for each line derived from the mean ΔCt of quadruplicate multiplex assays. Horizontal bars show the geometric mean for all sub-lines (“*” indicates p-value < 0.05, “**” indicates p-value < 0.01).