Fig 4. Cytotoxicity of LaFr26 and oxyopinin-2b to LX22 and BEN cells, but not to U87 or T98G cells.

(A and B) LaFr26 and oxyopinin-2b were added to the media of LX22 cells, and the cell viabilities were measured 30 min after (ANOVA followed Student’s t-test, vs 0 μM, n = 6). (C) LX22 cells were incubated with these peptides (10 μM) in the presence or absence of a K⁺ channel blocker, BaCl₂ (1 mM) and viability were measured. The addition of Ba²⁺ inhibited the cytotoxicity of peptides, indicating the K⁺ channel current dependency. (D and E) LaFr26 and oxyopinin-2b were added to the media of BEN cells (n = 6). (F) The addition of Ba²⁺ again inhibited the cytotoxicity to BEN cells. (G, H, and I) LaFr26 and oxyopinin-2b were added to the media of U87 or T98G cells. No cytotoxicity was observed. (J) Resting membrane potentials of U87, T98G, LX22, and BEN cells (n = 10, 5, 7, and 5).