FIGURE 4.

Temozolomide (TMZ) resistance of glioblastoma (GBM) cells is regulated upstream of the DNA damage response. A, The indicated GBM cells were treated with TMZ for the indicated time points. The cell lysates of each of the treated cells were subjected to immunoblotting using the indicated primary antibodies. The antibody against beta‐tubulin was used to confirm the amount of protein in each sample (upper). In addition, the results of immunoblotting were evaluated and normalized according to the value at the time point 0 h, and the values obtained were presented as the average of the results of all time points (lower). ^** P <.01. B, The indicated GBM cells were treated with ACNU, CCNU, or TMZ. After 9 h, the cell lysates of each of the treated cells were analyzed by immunoblotting using the indicated primary antibodies as in (A) (upper). The quantitative results of immunoblotting were also evaluated (lower). ^** P <.01. C, The cell lysates of the indicated GBM cells were subjected to immunoblotting analysis using the indicated primary antibodies (left). The quantitative values of the immunoblotting relative to those of GAPDH are shown (parental cell = 1) (right). ^** P <.01