Action mechanism of 6h for anti-proliferation of NCI-H522 non-small cell lung cancer cells. (A) Compound 6h, vincristine, vinblastine, and paclitaxel were incubated with pure tubulin proteins in GPEM buffer. Alternation of tubulin assembly was recorded at absorbance 340 nm. (B) Cells were treated with vehicle (DMSO, as control), 6h (10, 30, and 100 nM), 100 nM vincristine, and 100 nM paclitaxel for 24 h. Cytosolic (S, soluble) and cytoskeletal (P, polymerized tubulin) fractions were separated and followed by Western blot analysis for detection of a-tubulin, b-tubulin, and b-actin protein expression.