Fig. 2. G5-7 blocks EGFR phosphorylation and cell cycle at G₂ phase to inhibit cell proliferation.

(A) Proliferation of various U87MG cell lines treated with a range of doses of G5-7. Data are means ± SEM (*P < 0.05, **P < 0.01, versus IC₅₀ value of U87MG, one-way ANOVA, n = 3). (B) Cell cycle analysis of arrest at G₂ phase. One representative experiment of three is shown. Data are means ± SEM (**P < 0.01, two-tailed Student’s t test, n = 3). (C) Analysis of the proliferation of human GBM explant neurosphere cultures derived from glioma cell lines NHNP (wild-type PTEN, EGFR-deficient), N08-30 (PTEN-deficient, EGFRvIII amplification), and N09-24 (PTEN-deficient, EGFR amplification). Data are means ± SEM (*P < 0.05, **P < 0.01, one-way ANOVA, n = 4). (D) Western blot analysis of EGFR signaling in U87MG/EGFRvIII and U87MG/PTEN cells treated with different concentrations of G5-7 for 6 hours. Blots are representative of three experiments.