TrkB expression confers increased migration in transwell assays.

A549 cells (2×10⁴) suspended in culture media were seeded in the upper chamber of transwell plates. After 18 h incubation, cells that migrated to the lower surface of the filters were fixed, stained with cresyl violet and quantiified by counting three randomly selected fields using a 10x objective. Bar, 200 µm. Bars, mean ± SEM.