Flupirtine

All salts and other chemicals were purchased from Sigma-Aldrich (Germany) or Merck (Germany). Using DMSO or PSS, drugs were freshly dissolved on the day of each experiment accordingly to the material sheet. Maximal DMSO concentration after application did not exceed 0.5%. Following concentration of drugs was used: phenylephrine (Sigma-Aldrich) and methoxamine (Sigma-Aldrich) ranged from 0.01 to 100μm; retigabine (Valeant Research North America), flupirtine (Tocris), QO58 (Tocris), QO58-lysine from 0.01 to 30μm; 3μm XE991 (Tocris).

The human lung adenocarcinoma cell line (NCI-H460) was obtained from Korea Cell Line Bank (Seoul, Korea). The cells were maintained in complete growth medium supplemented with 10% fetal bovine serum (WelGene, Korea) and 1% antibiotics (Sigma-Aldrich, St. Louis, MO, USA) in an incubation system at 37 °C with 5% CO_2. The cells were harvested using 1% trypsin-EDTA (Sigma-Aldrich) when they were in the logarithmic phase of growth, for SP analysis. Hoechst 33342 and fumitremorgin C (ABCG2 blocker) were purchased from Sigma-Aldrich. The anti-cancer drug gefitinib (Santa Cruz Biotechnology, CA, USA), tetraethylammonium (TEA, Sigma-Aldrich), 4-aminopyridine (4-AP, Sigma-Aldrich), and flupirtine (Tocris Bioscience, Bristol, UK) were used to blockade cell growth.