Figure 1

Colony formation of glioblastoma cells after treatment with RT and/or CT with TMZ and/or VPA. T98G (A), U251MG (B), or U87MG (C) tumor cells were treated with TMZ (20 μM) and/or VPA (0.5 mM) alone, or in combination with RT. The dose-dependent clonogenic potential was determined after 2 weeks of incubation. The colony number (100%) of untreated cells was set as 1, and the reduction of the colony number due to treatment was calculated accordingly. Data from one experiment representative of at least two independent experiments is shown (n = 3). Mean values (±SD) are displayed. Gy, Gray; RT, radiotherapy; CT, chemotherapy; w/o, untreated control; TMZ, temozolomide; VPA, valproic acid; # P < 0.05, ## P < 0.01, ### P < 0.001 (TMZ ± RT against w/o ± RT), *P < 0.05, **P < 0.01, ***P < 0.001 (TMZ/VPA ± RT against w/o ± RT), + P < 0.05, ++ P < 0.01, +++ P < 0.001 (VPA ± RT against w/o ± RT).